Could Ranma ever stand up to Dragonball /DBZ ?

[lwf58]

Yes, all true. Note that my statement was that he no longer required the opponent to follow him in a spiral, not that a spiral did not need to be made with hot and cold opposing forces.
It was established early on that the biggest weakness of the Nichiezu version of the HSH was that it didn't work without the opponent's cooperation. The person being fought had to generate hot ki, and maintain it while being led in a spiral. If the opponent either stopped putting out hot ki, or did not follow the spiral while chasing the person attempting the HSH, it fizzled.
Ranma's later variations still required a spiral, but he adapted the HSH so that he could make the spiral alone, without the opponent. It also still required a source of hot temperature, but his variation could use any ambient hot source, not just the opponent's ki.
The variations of the HSH were:
* Heavenly Dragon Blast Revised: Horizontal Spiral (Hiryū Shōten Ha Kaiteiban: Gedan Rasen): The unique situation offered by Natsume and Kurumi's Hiryū Carimbou attack made this possible. The spiral created from Kurumi's ribbon radiated hot ki; Ranma gathered the hot ki from the ribbon to create the whirlwind. Since none of the combatants were radiating hot ki, Ranma used the whirlwind to push Akane into her opponents, the flying kick of doom. The side effect was the nullification of Natsume's own ki bolt; being cold ki itself, it would weaken the whirlwind, but, since the hot ki in the spiral is overwhelming, the effects were negligible. (This is the best rationalization that can be made from this alternate and anime-only attack.)
* Descending Dragon Shot (Hiryū Kourin Dan): Ranma discovered that the Hiryū Shoten Ha is ineffective against Herb, who knows of the attack (and thus managed to change his ki aura in time to lessen the effects of the whirlwind). But, Ranma noticed that excess hot ki gathered up in the sky. He created another whirlwind, allowing Herb to throw him into it. While in the air, Ranma gathered the hot ki and, with his own cold ki, fired himself downward, straight into Herb, for the final attack. It appears quite like a downward Moko Takabisha, but larger and much more deadly, backed by gravity and ki together.
* Ice Dragon Breakthrough (Hiryū Hyou Tōppa): This is Ranma's final attack against Saffron in volume 38 of the manga, completed with the aid of the Phoenix people's artifact which produced an icy cold touch based effect. Ranma planned on throwing a whirlwind though a channel of cold air surrounded on both sides by the hot air from Saffron's blasts, and that in the swirl in the middle the whirlwind would become highly concentrated, squeezing the cold spiral into a razor's edge. He was unable to find an opportunity to use the move until Akane threw her frozen doll form at Saffron, tunneling through Saffron's heat and giving a Ranma a small channel of cold air to fire the Hiryū Hyou Tōppa. The refined Hiryū Shoten Ha drilled straight through Saffron's chest, defeating him.
* Heavenly Dragon Searching Blast (Hiryū Gyōten Ha): Also used in volume 38 of the manga. Akane was dying and only the water from the Dragon Faucet could save her. Ranma, falling from the sky, had no time to get Akane to the water. Instead, he channeled all his energies into the whirlwind. The whirlwind was forced downward, then curved as it reached the Dragon Faucet. It brokes the Faucet, causing the Dragon Head to spew water into the sky. In this way Ranma saved Akane's life, but also destroyed an opportunity to remove his curse.
So the tools are there. Ranma could use variations of the HSH against the Dragonball crew. But something to note is that he can't use any variation of the technique without outside conditions allowing for it. He has to wait for or cause the environment or the opponent to create the conditions under which he can use it. He definitely cannot use one out of the blue, or create hot ki himself because he has to use the soul of ice technique to provide the "cold" side of the equation.

[FOG3]

Sorry maybe i used the wrong word when i used micron....Because clearly no blade known to man can slice several feet of stone near instantly without causing friction and super heating the stone causing explosive presure build up. To do that it would have to be virtually thiner than a molocule and seperate the molecules. I would normally define that as impossible, but it is clearly done on this page with the more basic Kijin
http://ranmahentai.ranma.ws/RanmaManga/Book28/RM28-129.html

Who said that's stone as you understand it? Rock in the Ranmaverse has very weird properties. For starts it's shown to virtually inertialess when thrown by and at people and things. Add to this other associated behavior and we're looking at a material that is a ceramic with properties one associated with styrofoam. There is nothing in the source material or the Viz translation that really forces this to not be the case. Super Soba arc shows stuff of similar apparent mass having inertia like it's supposed to.
Of course, at that point that point all the median strength figures drop to within nominal limits for a normal human. Dexterity and adaptability drop to within human norms on the weak side due to being extremely slow in picking up such a simple pattern as associated with ice skating. Incidentally this actually is how the median version more or less behaves.
Micron is a unit of measure that can also be expressed as a micrometer, so by daring to invoke it you invoked Physics. The above indicates what happens when you force the issue on physics under proper analysis. Oh and a pressure difference that maxes out at 1 atm, degraded in passage like that, using a fluid like air isn't exactly going to do much. The air lacks all of the material properties to make a good cutting instrument, and thus if you fix that the material properties of that object will adjust to respect such. You use knowns to derive unknowns, respecting the principles, sir.
They never did anything worth making a fuss over to animal targets. So really you can either stop trying drag real physics as a fanboys attempt to bolster their argument, or in the spirit of this we can arrange a catgirl to claw your eyes out. Your choice.

As to the other move i won't argue about it's limits as they are never deffined. As far as i rember the move is used once in the serries and that is against the Sai Dai Kyuu Kijin Raisu Dan that it appears to block and contain.

Yes Ranma loosens the ground so the vacuum will suck it up, collects various junk in a bag, setting up a trap so that when a now aggravated Ryu fires the only attack he has it'll back fire on him by pulling the surrounding dirt and cuts the wrap, the the junk acting like a sandbag barrier protecting him, so all the junk is released right on top of Ryu. It's a simple, basic trick that should be obvious in the hows and whys of its operation. No real magic tricks involved beyond cramming in a little more junk then he has any right to cram in there.

* Ice Dragon Breakthrough (Hiryū Hyou Tōppa): This is Ranma's final attack against Saffron in volume 38 of the manga, completed with the aid of the Phoenix people's artifact which produced an icy cold touch based effect. Ranma planned on throwing a whirlwind though a channel of cold air surrounded on both sides by the hot air from Saffron's blasts, and that in the swirl in the middle the whirlwind would become highly concentrated, squeezing the cold spiral into a razor's edge. He was unable to find an opportunity to use the move until Akane threw her frozen doll form at Saffron, tunneling through Saffron's heat and giving a Ranma a small channel of cold air to fire the Hiryū Hyou Tōppa. The refined Hiryū Shoten Ha drilled straight through Saffron's chest, defeating him.

What do mean drilled straight through his chest? No damage was shown to anything beyond the legs which fragmented off like shards of crystal. I've checked on that twice in recent history and I didn't notice any damage to Saffron's person beyond that. Further that Kima's explanation, in the Viz translation, is he ran out of energy and had to revert with no mention of termination of life functions tends to make me doubt that interpretation.

[Seraphim]

What do mean drilled straight through his chest? No damage was shown to anything beyond the legs which fragmented off like shards of crystal. I've checked on that twice in recent history and I didn't notice any damage to Saffron's person beyond that. Further that Kima's explanation, in the Viz translation, is he ran out of energy and had to revert with no mention of termination of life functions tends to make me doubt that interpretation.

It did actually go through Saffron's chest almost like spear, if it shattered his legs wouldn't the armour attached at his waist shatter as well?
EDIT: I think it's his legs hiding behind his cloak-thingy.

[lwf58]

These are the two pages in question.
http://ranmahentai.ranma.ws/RanmaManga/index.html
http://ranmahentai.ranma.ws/RanmaManga/index.html
It's very hard to really tell where the hit lands, because the drawing of the end of the whirlwind is vaguely done. It seems to be somewhere around the solar plexus, which would be lower chest/upper abdomen. You can call it either way, really.
As for the fragmentation, it looks like it started from his lower legs and is working its way up. Best guess is that it's a side effect of using the Gekkaja as part of the attack. No matter how you look at it, it's not directly related to the actual hit, because the freezing would be radiating out from his midsection if it were.

[claymade]

Yes, all true. Note that my statement was that he no longer required the opponent to follow him in a spiral, not that a spiral did not need to be made with hot and cold opposing forces.

Ah, gotcha. Sorry about the misunderstanding.
So then, as long as someone (or something) is creating a hot-cold spiral of the appropriate dimensions, he'll have a shot at pulling it off. The crux of the matter then becomes setting up things such that the spiral can be completed before he gets taken out, or before his foe disrupts the spiral somehow. (Plus the whole DBZ-flying problem.)
An interesting challenge... Can't think of anything offhand, but it certainly feels as though there should be a way. And if there is, Ranma can generally be relied upon to find it...

[three headed dog]

First off I want to state my position on Ranma vs DB characters. He stands very little chance and the Hiryu Shoten Ha will more than likely be nearly useless since DB characters would most likely be able to fly out of the tornado or just power-up fast enough to tear the tornado apart (might be good for a distraction or something though).

He has to wait for or cause the environment or the opponent to create the conditions under which he can use it. He definitely cannot use one out of the blue, or create hot ki himself because he has to use the soul of ice technique to provide the "cold" side of the equation.

Small nitpick but Ranma doesn't have to use the soul of ice at all depending on circumstances he could provide the hot ki while the opponent or environment provides the cold. Of course there is nothing stopping him from creating hot ki to heat the environment then switch to the soul of ice providing both the hot and the cold needed. But basically as things stand (possible that he eventually figures away to provide both simultaneously like in a fanfiction I read in which he found a way to heat one hand and freeze the other) Ranma either needs his opponent or the environment to provide either a cold or hot aspect unless he is given time in which case he could create all required aspects. (set stuff on fire, use his own ki to heat/cool the area, etc...)
I don't think Ranma needs to create much of a spiral to throw a Hiryu Shoten Ha? In these pages http://ranmahentai.ranma.ws/RanmaManga/ ... 35-040.gif, http://ranmahentai.ranma.ws/RanmaManga/ ... 35-041.gif the heat is provided by Genma and Soun but there appears to be no running in a spiral (they run directly at her). She probably does twist her arm into a partial spiral but it seems to me that everyone was surprised and this tornado was formed pretty much out of the blue with little to no spiral. This tornado was very weak and lasted only moments so against many of his opponents would just buy Ranma a few seconds time and be totally useless against a DB level fighter.
My view of the Hiryu shoten ha is that it requires three aspects two opposite energies (easiest two to use would be hot and cold but others are probably possible) and mixing them into a spiral. The amount Ranma needs to contribute is dependent on the amount available. If Ranma wants a weak tornado or a breeze very small amounts of each aspect is needed. larger spiral, or more heat, or cold used more powerful the tornado. If one of the aspects is larger then Ranma has to provide less i.e. in an area with lots of heat or cold a smaller spiral is needed to create a large tornado. Ex. breaking of the dragon tap. Since there was a large amount of heat in the air and Ranma was still cold he needed only a small spiral to create the tornado.

being extremely slow in picking up such a simple pattern as associated with ice skating.

I have a theory on that. I don't think it has much to do with Ranma's learning ability since we are shown in several instances that Ranma learns at an increased rate (Umisenken, Ranma's surprise that Ryu hadn't figured out how to do the Umisenken after seeing it, Colognes surprise at Ranma figuring out the Hiryu Shoten Ha so quickly, learning entire styles overnight, Akane even mentions Ranma is a quick learner prior to the Romeo and Juliet arc, etc...) My theory is this besides Ranma's anger at Mikado clouding his thoughts some the reason I think Ranma was having so much trouble with ice skating is because of another technique he knows. The theory I have is that the same technique that Genma and Ranma use to walk on things that should not be able to support their weight (such as the fence holding Genma's Panda form or Kuno's sword) makes it so Ranma has difficulty on slippery surfaces this would explain why he had so much trouble on the ice and why he is always slipping on banana peels and such. My other theory is she did it because it was funnier that way and the instance should be ignored since there is more evidence for Ranma learning techniques and stuff fast than against and I generally base my opinion on the side with more evidence for it.

[claymade]

Of course there is nothing stopping him from creating hot ki to heat the environment then switch to the soul of ice providing both the hot and the cold needed. But basically as things stand (possible that he eventually figures away to provide both simultaneously like in a fanfiction I read in which he found a way to heat one hand and freeze the other) Ranma either needs his opponent or the environment to provide either a cold or hot aspect unless he is given time in which case he could create all required aspects. (set stuff on fire, use his own ki to heat/cool the area, etc...)

It's debatable whether it would be possible for him to dump enough heat into the surrounding area and then switch, but more fundamentally it mitigates the main point of the Hiten Shoryu Ha, which is to take on a more powerful enemy by using their own strength against them. If he's just going to be using his own strength for the whole thing, dividing his efforts between hot and cold, I'd imagine he'd get far more efficient use of power (in most cases) just hitting his opponent with a Moko Takabisha.

I don't think Ranma needs to create much of a spiral to throw a Hiryu Shoten Ha? In these pages http://ranmahentai.ranma.ws/RanmaManga/ ... 35-040.gif, http://ranmahentai.ranma.ws/RanmaManga/ ... 35-041.gif the heat is provided by Genma and Soun but there appears to be no running in a spiral (they run directly at her). She probably does twist her arm into a partial spiral but it seems to me that everyone was surprised and this tornado was formed pretty much out of the blue with little to no spiral.

My own read on such situations is that there was actually a spiral performed, but Takahashi didn't bother going through all the intermediate steps in order to save on page space. Consider this example:
http://ranmahentai.ranma.ws/RanmaManga/Book13/RM13-149.jpg
Here Cologne (as far as we're shown) isn't shown using a spiral either, just an uppercut--and yet from that, Happousai seems to recognize what Ranma was trying to accomplish with his spiral. Thus, I tend to suspect that for most of the trivial uses of the HSH, it's just a space-saving measure, but that the spiral was actually present.

[three headed dog]

If Ranma does create a tornado totally under his own power it will undoubtably be less powerful and be an inefficent use of energy in most situtations.
Those two examples of the Hiryu Shoten Ha aren't good comparisions since one is a flashback which Cologne had forgotten about and the other was in real time where the opponents (Soun and Gemna) were running directly at the mirror clone. Anyways I still think that a spiral was used (the arm corkscrewing) just no running in a spiral or creating a spiral on the ground (this was also the weakest of all the tornados created in the manga). The last tornado Ranma used to break the dragon tap and the one he used to drill into Saffron similiarally did not require Ranma to create much of a spiral (there appeared no spiral in those instants as well, though you can argue that there was a spiral since Ranma had been in a tornado but since the new tornado was in a different direction I would think that he would have had to create a spiral motion in a different direction - the direction that he wanted the new tornados to go).

[FOG3]

It's very hard to really tell where the hit lands, because the drawing of the end of the whirlwind is vaguely done. It seems to be somewhere around the solar plexus, which would be lower chest/upper abdomen. You can call it either way, really.
As for the fragmentation, it looks like it started from his lower legs and is working its way up. Best guess is that it's a side effect of using the Gekkaja as part of the attack. No matter how you look at it, it's not directly related to the actual hit, because the freezing would be radiating out from his midsection if it were.

Acknowledged especially about the Gekkaja's influence. I just felt that drilled through his chest didn't seem to accurately describe what was going on there, ne?

Small nitpick but Ranma doesn't have to use the soul of ice at all depending on circumstances he could provide the hot ki while the opponent or environment provides the cold. Of course there is nothing stopping him from creating hot ki to heat the environment then switch to the soul of ice providing both the hot and the cold needed. But basically as things stand (possible that he eventually figures away to provide both simultaneously like in a fanfiction I read in which he found a way to heat one hand and freeze the other) Ranma either needs his opponent or the environment to provide either a cold or hot aspect unless he is given time in which case he could create all required aspects. (set stuff on fire, use his own ki to heat/cool the area, etc...)

Causing major temperature change to an open environment? Since when did he jump about a hundred rungs? If it''s that simple why don't you try openning up your home to the enviroment and trying to make it cold when its hot and hot when it's cold with your heat pump. I take no responsibility on how much your bill jumps during an attempt at this because any reasonably sane person can see what I'm getting at.

I don't think Ranma needs to create much of a spiral to throw a Hiryu Shoten Ha? In these pages http://ranmahentai.ranma.ws/RanmaManga/ ... 35-040.gif, http://ranmahentai.ranma.ws/RanmaManga/ ... 35-041.gif the heat is provided by Genma and Soun but there appears to be no running in a spiral (they run directly at her). She probably does twist her arm into a partial spiral but it seems to me that everyone was surprised and this tornado was formed pretty much out of the blue with little to no spiral.

I am sorely tempted to check up on the Viz translation of that, as it resembles the standard Sauron maneuver a little too much, and I know those Project guys will simply slip fanon things in. That said, nonsense. Guess what you forgot you needed? Something actually stating or making a point about there actually not being a spiral. They have a surprised reaction to her being able to do a HSH, but nothing about spiral or no spiral. Thus you have _no evidence_ of absence, and as absence of evidence is not evidence of absence you're stating a capability with exactly zero support. While that's fine for a subjective opinion it has no more weight as an objective statement then someone taking about a UFO invasion in RL.
Besides which doing that entire thing out for one of her standard exit stage left of inconvenient characters would be unnecessary and breaking with the flow of the story. So from a writers standpoint it actually would have been a bad thing to go to all the trouble to show it.
The ones around Saffron involved either setting up the matrix on the ground in ice, which allowed it to just keep going or involved what amounted to eddy currents. As his little diagrams shows the interaction of the stupidly hot air and his jet of cold was supposed to cause it to spiral. Given how much the entire thing is one extended dump on RL thermodynamics picking nits on it is rather pointless. Hot air such that it would support your weight against gravity in an equilibrium state indeed. Anyone who wants to even pretend to force RL physics on this series has to admit gravity is well below Earth standard after something like that.

I have a theory on that. I don't think it has much to do with Ranma's learning ability since we are shown in several instances that Ranma learns at an increased rate

when compared to a rock. Poor rock.
Should Goku's 100x _completely canon_ feat that's better then best Ranma fan argument I've ever seen in the same area be brought up? You know, where Roshi tells him how it's going to take him _years_ to learn the KameHameHa after firing one off and Goku just turns around and fires off one of his own.

Umisenken

Took him what a week, with Genma showing him the only real trick, and getting the scroll from mama? Yeah, yeah he stole the foundation and other stupid stuff. In the actual fight the only thing that was new was sneaking around, carrying a wrap, and a few attack moves that could at the concept level be picked up in an hour easy. Aura suppression was in the curriculum several volumes ago (HSH), and while there's enough for people to hold a subjective view that he can go invisible, there's not enough for it be done so objectively. Hence 90% of it was stuff he already knew with just a little tweaking here and there and maybe an unusual concept thrown in.

Ranma's surprise that Ryu hadn't figured out how to do the Umisenken after seeing it

There's no such thing. He gives some smack during the fight about you'll learn the Umisen ken by me beating it into you, but that's it. Relatively standard fight smack talk, and utterly meaningless in any avenue you're trying to use it in.

Colognes surprise at Ranma figuring out the Hiryu Shoten Ha so quickly

Cologne: We're going to teach this to you in a week.
Almost a week later.
Cologne: Darn this isn't working, get Ryouga over here.
Ryouga gets his rear over there.
Cologne: Oh oops, I forgot to teach him the uppercut. Oh well, it appears he figured it out anyway.
Reality check: Just like SSH this is a technique that's apparently so utterly intuitive you can do by accident and he's never been particularly fast at picking them up. The SSH was literally stated as an easy, anyone can learn technique by the Miner who handed it over.

learning entire styles overnight

[sarcasm]Yeah, learning three weapons you already clearly knew how to use when you made Akane look bad, watch for how many days, and use 99% already present skills, tactics, etc is a great feat.[/sarcasm]

My theory is this besides Ranma's anger at Mikado clouding his thoughts some the reason I think Ranma was having so much trouble with ice skating is because of another technique he knows. The theory I have is that the same technique that Genma and Ranma use to walk on things that should not be able to support their weight (such as the fence holding Genma's Panda form or Kuno's sword) makes it so Ranma has difficulty on slippery surfaces this would explain why he had so much trouble on the ice and why he is always slipping on banana peels and such.

If he was a tenth of the man you wish to believe he is he'd simply spend a few minutes watching the other skaters leg movements and pick up on both the leg movement pattern and technique for braking. Then proceed to have only minimal problems in basic maneuvers.
An hour lesson is reasonable, at a day it's justified in calling you clumsy, when a week later you still have basically zero control on the ice you're seriously underachieving. All that's really involved is a few basic movement patterns and keeping your balance. We're talking just the basic level of control here, not figure skating or anything that's actually complicated.

My other theory is she did it because it was funnier that way and the instance should be ignored since there is more evidence for Ranma learning techniques and stuff fast than against and I generally base my opinion on the side with more evidence for it.

Of course she did it because she thought it'd be funny. Everything that happens in that manga happens because she thinks it'd be funny. That's the point.
So zero evidence is better then some evidence in your book? Evidence in this sense is related to proving things, not subjective opinions. You have brough forward nothing other then evidence he's not a literal rockhead, which had already been conceeded to you.

[claymade]

Of course, at that point that point all the median strength figures drop to within nominal limits for a normal human. Dexterity and adaptability drop to within human norms on the weak side due to being extremely slow in picking up such a simple pattern as associated with ice skating. Incidentally this actually is how the median version more or less behaves.

The problem with interpreting it that way is that even in the Ranmaverse we have all kinds of "normal" humans running around who are astonished by the freakish displays of strength, speed and durability that the relatively few martial artists display.
You don't see Hiroshi and Daisuke doing multi-story leaps, nor Yuka and Sayuri lifting huge boulders. Akane herself can take out a whole mob of her classmates with ease, and Ranma and his peers are all orders of magnitude more powerful than her.
No matter which way you look at it, Ranma & co are on a completely different level than the "standard" human being, even in their world.

[sarcasm]Yeah, learning three weapons you already clearly knew how to use when you made Akane look bad, watch for how many days, and use 99% already present skills, tactics, etc is a great feat.[/sarcasm]

Except that that's not the only instance of him learning a new style overnight. A better example would be learning the Martial Arts Tea Ceremony style, which involved not only all sorts of techniques and weapons he had never tried before, but also learning to do the whole fight under a completely new method of locomotion. And yet, after only one night of training he owns his opponent conclusively, drawing some grudging compliments to his skill from the school's master, who had up until the fight made no secret of her disdain for "Miss Clumsy."

Cologne: We're going to teach this to you in a week.
Almost a week later.
Cologne: Darn this isn't working, get Ryouga over here.
Ryouga gets his rear over there.
Cologne: Oh oops, I forgot to teach him the uppercut. Oh well, it appears he figured it out anyway.

Um, what? By my count, it's:
Night One: Cologne blows Ranma, Genma and Ukyo away with the HSH. Ranma immediately deduces that the key was the spiral pattern she'd led them into, to which Cologne replies: "That's my son-in-law. And after seeing it only once..." Ranma announces he'll master it by morning.
Day One: The sun rises, and Ranma has in fact mastered the spiral portion. Ryouga shows up, but isn't able to bring himself to fight Ranma at full strength, thus completely stymieing their efforts.
Night Two: Ranma appears to rape Akane, making Ryouga furious. Ranma then blows him away with the HSH.
And that's it. Roughly 24 hours, much of which was taken up waiting for an opponent he could actually use it on. Unless I missed a page somewhere...?

Aura suppression was in the curriculum several volumes ago (HSH), and while there's enough for people to hold a subjective view that he can go invisible, there's not enough for it be done so objectively. Hence 90% of it was stuff he already knew with just a little tweaking here and there and maybe an unusual concept thrown in.

Whether or not he's technically "invisible", it reduces his opponent to firing blasts around randomly in an attempt for a lucky shot. That's an order-of-magnitude difference of effect over anything we've seen the Soul of Ice accomplish, whatever he was doing.
Not to mention that, even if it was only a slight modification of Soul of Ice (which there's no real canonical proof of) he learned that in just a handful of hours--so that really doesn't buy you much at all.

Of course she did it because she thought it'd be funny. Everything that happens in that manga happens because she thinks it'd be funny. That's the point.

Which is why it's tenuous to say that Ranma's "on the weak side" based on that one event. It's like saying Akane isn't a skilled martial artist because she can't learn to swim. Some things are just plot-determined.
However, when you have both those who like and those who dislike the guy commenting favorably on his skill, that's some pretty significant evidence that he does indeed have some mad skills within the context of his universe.
Of course, when you start moving to other universes, that's when you have to make conversion decisions. We know Ranma's a quick learner in his universe--how would that translate into the DBZ universe? How "hard" is a Kamehameha to learn--what's the statistical spread between the years that it would take "most people" and Goku's near-instant usage of it? How long would it take those same "most people" Roshi was referring to learn the HSH or the Amaguriken?
We can't nail it down for certain, and this is where the author's "fudge factor" comes into play. Depending on how the author justifies it, it could believably play out any number of ways. That's part of the freedom of fanfictioning, and what can keep crossovers interesting as scenarios play out any number of different ways.

[Pale Wolf]

what's the statistical spread between the years that it would take "most people" and Goku's near-instant usage of it? How long would it take those same "most people" Roshi was referring to learn the HSH or the Amaguriken?

And you also have to worry about the style issues. Ie, what precisely is required to learn it. Skillwise it could be pitifully easy and just require years to build up the power to actually achieve any results - in fact I'd be inclined to believe that, considering DBZ's focus on power.

[Draconis Stelanaris]

I'm with PaleWolf on the Kamehameha. For all apearences it is just a few steps of low complexity, 1. focus energy into point. 2. Aim energy. 3. Fire. Ok, the focusing energy is the hardest part that I can see and the Rei gun from YYH acts in the same way just on a lesser scale and Yusuke got it in the first go after being told how. All it is is a matter of power and to a lesser extent control. Any one who is capable of Ki control and has the raw power could pull it off.
So not realy a good exsample of a learning curve for goku. Just relitive power.

[three headed dog]

Took him what a week, with Genma showing him the only real trick, and getting the scroll from mama

By my count it did not take him a week to learn it took him about 2 days at most. Genma used the Umisenken on Ranma then Ranma practiced that night (after he woke up he replaced the stuff in Akane's room, stole part of Souns paper, and the kitchen floorboards then sneaks into Akane's room at night) the following morning Akane goes to give the challenge and Ranma sees a part of the technique that was on the envelope later same day the fight commences.
No spiral used Hiryu Shoten Ha's is really only my opinion because I can't really prove it but you also can't disprove it - all you can really say is that the author was just lazy but that doesn't disprove it. My opinion is based on that they run directly at her, we do not see anything that shows her moving even the least bit in a spiral - no movement lines until after the fist is thrown then spiral lines show up. Anyways there is no spiral movement for the last Hiryu Shoten Ha -the one used to break the dragon tap (can argue that since he was in a tornado there was a spiral but since the new one he created went in a different direction he would most likely have needed to creat a spiral in the direction he wanted the new tornado to go). If you want to check a different translation you can check http://www.wot-club.org.uk/RanmaFAQ/ they have text translations for v20,23-38. Personally I think this is the best translation because it gives more details ex vol 38 explains how a sports analogy was used which is not told in either the viz or fan-scan versions.
As for the ice skating. He was only on the ice for about a minute or so before Mikado showed up and then he ran out changed forms beat mikado up then left. The next time he was on the ice was the start of the actual match and during the match he was able to skate in a straight line almost imeadiately he just hadn't figured out how to stop or turn yet but gets better as the match went on. Anyways my theory did not matter that he was doing the technique right or not in my theory he was trying to walk like he always walks i.e. able to walk on things not strong enough to hold his weight and that while he was doing that it would cause him to fall since on ice he needed his weight.

Causing major temperature change to an open environment

He doesn't have to cause a major temperature change in the environment he only needs to create an area where the temperature is unbalanced long enough to spiral the unbalance and I never specified where he was doing this so he maybe in a partial closed envirnment - i.e. walled on a couple sides or place with an over hang causing the heat/cold to be trapped long enough or he could create one within a structure (like a room) this should be feasible.

[antimatterenergy]

SSH this is a technique that's apparently so utterly intuitive you can do by accident

If this were true why is it that very few people in the Ranmaverse throw ki blasts? Also Ranma had no trouble doing the Shi Shi Hadoken at all. He was able to do it on his first try it just had no power and fizzled out. The problem he had was figuring out that it had to be focused through an emotion (depression) once he figured out that you had to focus through emotion he was able to throw them whenever he wanted (though he had trouble isolating the emotion of depression since he is not easily depressed nor does he stay depressed when he does get depressed.)

[claymade]

Anyways there is no spiral movement for the last Hiryu Shoten Ha -the one used to break the dragon tap (can argue that since he was in a tornado there was a spiral but since the new one he created went in a different direction he would most likely have needed to creat a spiral in the direction he wanted the new tornado to go).

Hmmm? I don't see why he would need to make the spiral itself spin in a reverse direction--under the principles of the HSH, it seems he'd just need to provide a new cold-aura-punch that's directed along the course he wants it to take. The whole point of the HSH is that the spinning hot air will get sucked along the path of the cold current. If he can provide that cold current--in the middle of hot air that's been set spiraling by his previous HSH--he should be able to direct it however he wants.

No spiral used Hiryu Shoten Ha's is really only my opinion because I can't really prove it but you also can't disprove it - all you can really say is that the author was just lazy but that doesn't disprove it. My opinion is based on that they run directly at her, we do not see anything that shows her moving even the least bit in a spiral - no movement lines until after the fist is thrown then spiral lines show up.

The problem is that, even as late as the first HSH he uses on Saffron, he still seems to need a spiral pattern--else, why would he bother with making the ice matrix in the ground if he could throw the HSH without it?
Not to mention that being able to arbitrarily throw a HSH with a simple uppercut given any appearance of a battle aura is so utterly overpowered that I find it inconcievable that no one would have ever commented on Ranma suddenly gaining that ability. And gaining it "offscreen", and with no explanation, stretches my disbelief far, far beyond the breaking point.
Far more plausible (to me) is that Takahashi simply compressed a few frames, rather than completely changing the rules for one of Ranma's core techniques without so much as a mention or an explanation.

And you also have to worry about the style issues. Ie, what precisely is required to learn it. Skillwise it could be pitifully easy and just require years to build up the power to actually achieve any results - in fact I'd be inclined to believe that, considering DBZ's focus on power.

Indeed... And even in terms of skill, things can be easier or harder depending on having learned other skills previously (as FOG3 pointed out). Goku, IIRC, was trained by Gohan, who was trained by Roshi originally, so many of the skills he had already learned could theoretically have been leading up to the Kamehameha to some degree. All kinds of room for fudging either way there.
Incidentally, speaking of the Umisenken, I recall there was some question previously as to whether it would be effective in hiding Ranma's presence against the DBZ fighters. I'll argue that it would work wonderfully; they might be more powerful than the Ranmaverse fighters, but I see no reason to mark them as more perceptive.
Heck, if they're used to dealing with planetary-level ki, then I'm certainly not going to afford them better chances than Ranmaverse fighters of detecting someone in the Umisenken. If a bug has a hard time finding a fellow bug due to a cloaking field, I wouldn't expect a giant to have an easier time locating that same bug.