Okay, this is sort of an idea I just came up for of a Sailor Moon, Nanoha A's, Ranma cross. Only the Nanoha universe isn't really touched upon. Only the Book of Darkness from Nanoha A's and the guardian knights it spawns are in it, there either is no, or they don't come, Space Time Admin Bureau, or Nanoha main characters.
Ranma, like Hayate, has the Book of Darkness from birth. It's actually something Genma stole because it looks valuable, and he found that after his son was born and he tried to hawk it off, that it kept somehow returning to Ranma's room. Not wanting to get into too much trouble, Genma returns the money, but decides, that if he's ever in a tough spot during the training trip, then he can sell the book and move on.
Genma discovers, however, that selling Ranma is much eaiser, and gets into a habbit of doing that.
Now, unlike Hayate, Ranma's magical strength isn't too small to power the book of darkness's drain on it's master. And initially, Ranma communicates with the book telepathically, although he never sees the book as it's kept in Genma's pack, and it tells Ranma about how he will one day command the Cloud Knights and helps teach Ranma basic math and reading and other things Genma neglects when Genma isn't paying attention to Ranma, it also advises Ranma in his martial arts practice, the book has been getting very close to being ready to awaken, when Genma begins the neko-ken training. The book doesn't have the power to interfere and protect it's master yet, but tries to get Ranma not to go through with the training, realizing how dangerous it is.
Ranma becomes resistant, and doesn't want to do the training, surprising Genma, who accuses him of being weak and forces him to do the training.
The Neko-ken takes advantage of Ranma's developing spiritual senses and imprints a feline mentality into his head, and the trauma of the experience causes a psychic backlash and Ranma looses a lot of memories, including those of the Book of Darkness. Ranma's body begins locking away most of Ranma's spiritual power and storing it up for brief use under the neko-ken, nearly completely cutting off Ranma's connection to the Book of Darkness, and blocking off Ranma's magical potential. The damage to Ranma's mind causes him to forget his mother, the Book of Darkness, and loose access to some of his mental potential, his mind re-gearing itself for an even greater forcus on martial arts and loosing some of the social graces Ranma had been developing.
Going to an all boys school with Ryoga there right after that makes Ranma's mental condition worsen from all the negative influences of the rowdy boys and the sparring with Ryoga. Genma takes off with Ranma again to China soon after that and without the book to advise him, Ranma becomes less independent from Genma, and Genma begins reversing some of the book's positive influence with his stupidity, all the while, Ranma is training and growing stronger, with occasional releases of power from going neko.
Things continue as cannon until the end of the manga. But something has happened, the Gekkaja was actually a powerful, but primitive and mostly powered by natural magic, rather than designed magic, magical control device. The great power Ranma displayed in the battle against Saffron was actually Ranma's great magical power being forced out and utilized using the Gekkaja, it, along with the fact that Ranma has begun facing his cat fears, such as during the Ghost cat arc, creates enough of a crack in Ranma's spiritual sheilds for Ranma to begin leaking magical power again, and starts to re-awaken the Book of Darkness, which nears the time for it's final awakening.
At the end of the manga, Ranma and Akane are shown walking to school together, during the walk, Ranma is splashed, as normal, and the magical shock of the change is enough for the book, which is now mostly re-awakened, to communitate with him for a brief amount of time and tell him how to undo his spiritual blocks. Ranma succeeds at this, and is able to communicate with the book telepathically, but only vaugely remembers it. During classes that day, Ranma surprises nearly everyone by being able to answer questions in class and staying awake, it's actually thanks to the fact that he's communicating with the book of darkness, which is helping him with meditation to unlock the spiritual and mental blocks Ranma subconciously created during the neko-ken. Finally, during a fight with Kuno at lunch, Ranma is able to burn off the excess neko-ken feline imprinting as much as he can, surpising everyone by using neko-ken moves. When questioned by Akane and Ukyo, Ranma explains that during the fight with Saffron, he was able to unlock some of the power of the neko-ken to win, and that it's causing a lot of memories to come back and increasing Ranma's awareness, but that he burned off the remaining cat power he'd stored in himself and it seemed like it wasn't coming back.
Even Nabiki is shocked that Ranma's been actually showing more inteligence and being politer than normal, and tries to quesiton him as well, but lunch is over, and everyone goes back to classes. Ranma, who's gotten most of his memories back by now, is becoming withdrawn and depressed at all the horrible mistakes he's been making and his rude behavior now that he's remembering how to behave properly. During PE he apologizes to Akane and Ukyo and Hinako-sensei (who has that period free and followed their PE class) for how rude he's been during the previous year, and how much trouble he's caused, and promises that now that he's thinking clearer, he's going to do his best to fix things and treat everyone nicer. Ukyo and Akane each take this the wrong way and think Ranma means he's going to get rid of the other fiancees in favor of themself, but do it politely and without loss of honor if possible, although they don't say this aloud.
Ranma asks the Book of Darkness about curing his Jusenkyo curse, but it says it doesn't know if the guardian knights will be able to cure it, and if not, Ranma will have to have them complete the book and awaken it's full power in order to cure the curse, since Jusenkyo is powerful ancient magic. By the end of PE, Hinako notices that Ranma's been rather withdrawn and contemplative, and thinks maybe the stress and chaos of his life is getting to him. She comes up with an idea.
Hinako follows Ranma and Akane and Nabiki home that evening and tells the Saotome's that Ranma's been showing a lot more inteligence that day, and that she wants to have him take an IQ test to see what his IQ is, and mentions that the last time her apartment had ever been clean was when Ranma cleaned it up when Ranma and Akane came over for studying, so she's like Ranma to come over and take an IQ test and then clean up her house and stay over for the night as it would probably be late by then. Akane wants to come along, claiming she wants to protect Hinako, but Hinako points out that she's plenty strong enough to defeat Ranma with her special techniques, and that Ranma's been less of a delinquient recently, and that IQ tests should only have the person taking them and the tester, so Akane agrees, so long as Ranma promises to stay in girl form, which Ranma does, saying it's no big deal if it makes Akane more comfortable. Ranma realizes that the book, which is ready to awaken fully at any time, could be awakened in private at Hianko's apartment, and makes a pretense of getting some schoolbooks, but actually sneaks out the Book of Darkness where it was hiding in Genma's pack.
Ranma takes the IQ tests when they arrive without the Book of Darkness assisting him, and afterwards while Hinako is scoring him he cleans up her apartment. It turns out Ranma is indeed a genius with an IQ over 200. While they are having a dinner cooked by Ranma, Hinako asks him why he performed so poorly before, and Ranma explains that the neko-ken had suppressed a lot of his inteligence and memories and that he'd finally gotten his full capabilities back through meditation. Hinako is very angry with Genma when she hears about the neko-ken, and promises to help tutor Ranma to catch up in school and reach his full potential for this new school year (start of Akane and Ranma's junior year, Kuno and Nabiki's senior). They work together to clean up the apartment, leaving Hinako really exhausted, and Ranma presses a sleep point on her after she falls asleep to make sure she stays asleep, then the Book of Darkness awakens at midnight.
Ranma introduces him/herself to the guardian knights, showing the curse and explaining the neko-ken and giving a shortened version of his life story and the current status of things in Nerima, the Knights are outraged at some of the things their master has had to go through and want revenge on the parties involved, but Ranma makes them promise not to hurt anybody unless they have to in order to defend the weak or him when he can't fight on his own, and not to kill.
Meanwhile, a dimension away, in the Sailor Moon dimension, Rei recieves a terrifying vision of worldly destruction, of the destruction of another dimension, filled with warriors and wild magic, which causes such violent repprecussions as to cause destruction in the Sailor Moon dimension and cause destruction of the world. She summons the scouts, who agree that the destruction of this other dimension must be stopped, and Sailor Pluto is able to identify it and using a power boost given her by Sailor Moon and Tuxedo Mask, they're able to create a portal there and go there, Sailor Pluto arranging for when they all go back, for them to find a way to go back to the same time as they left at, using the time gates, so that their families wouldn't worry about them.
Since Japan is mostly the same as in their home dimension, just with a greater warrior culture and more common magic, the Sailor Scouts are able to use some of Sailor Pluto's money to buy a bunch of apartments in Hinako-sensei's aparment complex, while in their civilian identities. Sailor Pluto also arranges for them to go to Furinkan High (mostly as freshmen (Japanese high schools are 3 years, as are their jr. highs) Neptune and Uranus as seniors, and Hotaru to Furinkan Jr. High) claiming that she's a rich heiress who grew up as an orphan and suddenly inherited a lot of money, so she adopted a bunch of orphans, Tuxedo Mask claims to have been an orphan as well, and Usagi's boyfriend, but he's allready a high school graduate and is saving up and studying for Medical College, he ends up getting a job at Dr. Tofu's to supposedly pay back a loan from Setsuna for his own apartment and save up for College, he's also quite impressed with Dr. Tofu's healing techniques, he's not at all impressed with the part time worker there Genma, who seems to cause more trouble than he helps.
During all this, the Knights get help making disguises/everyday clothes for themselves from Ranma, Zaphira takes the form of a normalish looking puppy dog, and the other three pretend to be tourists, cousins of each other from Germany, looking for some distant Japanese relatives of Vita's, and that they spotted Ranma leaving Hinako's the next morning, and thought that Ranma looked a lot like Vita (both have watermelon red hair and dark blue eyes and wear their hair in pigtails and are petite, at least compared to Ranma's girl form). They explain that they have nothing but the clothes they are wearing since their luggage got stolen, and they need to stay in Japan at least until they've earned enough for return tickets. Nodoka, seeing that Vita does indeed bear a resemblance to herself and Ranma, invites them to stay with her at the now repaired Saotome-ke, Vita is lent some of Akane's old clothes, Shamal some of Nodoka's spares, and Signum some of Kasumi's. Nodoka also decides it's high time she spent more time with her son, and has Ranma come with her as well, but refuses to allow Genma to come back until he pays off some debts with the money he's been saving up from his job at Dr. Tofu's because she's angry at him since she got a call from Hinako about the neko-ken. Akane at first is being pressured to go along to, but Nabiki dupes the old men into thinking 'absence makes the heart grow fonder' and also points out that there wouldn't be enough extra room with all the guests staying there.
It's arranged for Signum to get money by teaching Ranma and Akane swordfighting in the afternoons, and working at Furinkan as a groundskeeper to keep the students in line during the day. Shamal also gets a job at Furinkan as a school nurse (since she also knows non-magical healing methods). Vita goes to Furinkan Jr. High.
Ranma meets the senshi in school, especially when Minako and Makoto start going after him, but Minako is to weirded out when his curse is revealed, and Makoto too shocked by the martial arts skill of the competition, so they've given up by the end of the day, instead insisting on becoming Ranma's friends. Through them, Ranma also becomes friends with Usagi, who ties with him in an eating contest, much to the shock of most of Furinkan, who also see Usagi match Ranma in running laps in PE (this actually shocks the other senshi as well, they hadn't realized just how fast Usagi could be) especially since Usagi is clumsy and trips when she tries to stop. (Causing Usagi to meet Shamal for a scraped knee) Akane and Ukyo don't like that a bunch of girls are trying to make friends with Ranma, and Ukyo tries to bully the girls away and Akane tries to bully Ranma away and make friends with the girls, who are shocked by the poor way Ranma is treated by Akane and the way Ranma just puts up with it. Later on, Ranma meets the outer senshi when he goes to Furinkan Jr. High to pick up Vita, who has made friends with Hotaru, who the outer senshi were going to pick up.
Michiru mentions she needs to go food shopping, and Vita reminds Ranma that his mother asked him to do the shopping and gave him a shopping list to be done for that afternoon, and Ranma offers to be the outer senshi's guide to the Nerima markets, since he knows the area pretty well having been sent to do shopping for Kasumi before. Ranma gets angry when the curse gets triggered and Haruka hits on her, because she thinks Haruka is a guy, Michiru scolds Haruka for being unfaithful and sends her home so she doesn't bother Ranma. Happosai shows up and tries to fondle onna-Ranma and steal Michiru's bra, but Zaphira shows up in his normal form when Happosai is escaping after bombing Ranma, wearing the knight armor Ranma came up with for him (Ranma only designed his Kinght armor so far since he was the only one who couldn't pretend to be human and wear normal clothes) and he defeats Happosai, pretending to be a super hero 'Kitsune Blue'. The two senshi sneak off and transform, because Zaphira is having trouble dealing with Happosai's speed and skill actually pinning him down for an attack without causing too much property destruction, and Sailor Saturn and Sailor Mercury also make public apparances and stop Happosai, and Sailor Saturn uses her healing powers to heal the burns Ranma got and the injuries Happosai caused some innocent bystanders to take, then they all sneak off and change back. Hotaru and Michiru return asking if Ranma is okay and saying they ran off to make sure they didn't get in the way in the fight and could tell it seemed to be over. Ranma relates to them the appearance of the magical super heroes, displaying confusion over the event, saying Nerima didn't have super heroes before, especially not magical ones, althoguh it had magical creatures attack it before.
Ranma finds out that Shamal can't cure the Jusenkyo curse, and decides, that since draining people's magical cores didn't really hurt them in the long run, as it could heal as long as they weren't drained to death, that it would be okay for the Knights to collect magical cores so long as they didn't kill anyone, so that they could complete the Book of Darkness. He comes up with Knight armor for the that makes them look different from their normal identities, with different hair and eye colors and hairstyles, distorted voices, and masks, so that they wouldn't be recongized. In their civilian identities, the Sailor Scout's magic is hidden, so they don't end up as targets, but Usagi encounters Signum draining Cologne after an intense battle, and transforms and tries to stop her, the battle is long and drawn out, Signum refusing to explain herself beyond that she seeks a cure to her master's curse and needs power for the cure, and refusing to trust and believe in Sailor Moon's power when she claims she's sure she can cure the curse, whatever it is, the other knights and Sailor Scouts appear, and Sailor Venus and Sailor Jupiter are drained, revealing their civilian identities, as is Cologne, and the Knights destroy Sailor Moon's scepter, Tuxedo Mask's baton and hat, and the weapons/tools of the outer scouts, the Silence Glaive, the Time Staff, the Space Sword, and the Mirror, much to the shock of the senshi, who thought those items were indestructable. Both groups decide to retreat when the Knights realize who the scouts are after draining Jupiter and Venus.
Sailor Mercury is able to figure out how the Knights can use their shells to gain temporary huge boosts in magical power, and that they're trying to fill up the Book of Darkness' pages, and that the more magical power and versitility someone has, the more pages they'd add to the book when they are drained. She explains that while in this other dimension, the scouts can't access their full powers by tapping their planetary manna, and have to rely on their own internal spiritual power to power their magic, meaning they can't use upper teir attacks or eternal forms.
Mercury also discovers how the Knights' weapons and magic work, explaining that they are similar to the Ginsuzishou in that they are powerful magical focuses that help you control your magic, but that they work more like the mercury computer in that they have magical programming, and that they have artificial inteligences, she says the only way the Sailor Scouts can match the Knights is if they also have similar devices and as versitle of magical abilities, including flight and sheilding techniques, and comparable weaponry. Mercury begins to work with Usagi, Luna and Artemis on upgrading/repairing the outer senshi's and Sailor Moon's and Tuxedo Mask's tools with a magical programming AI system and magical cartridge system.
Ranma, after seeing the states Makoto and Minako are in when he goes for tutoring with Hinako-sensei, tells the Knights to leave the scouts, his friends, alone, and gives them various magical locations and people away from Nerima to try and drain from, including the Orochi at Rozengenwa and the Jusenkyo area with Saffron. During this time, Ranma is also trying to learn the Knights' style of magic, Ranma is slowly learnign to create rune arrays without aid of a control device (the book isn't fully awakened yet) and is also learning to be able to transform into an animal form and become a changeling, his form will be a cat because of the neko-ken, but he hopes to cure the remaining damage done by the neko-ken by mastering his animal form, Ranma also begins studying the magical texts and programming of the Book of Darkness as his understanding of magic increases, he makes sure the Knights work slowly, because he's got to have a good excuse for his curse getting cured, especially since he doesn't think some of his rivals, such as Ryoga and Mousse, deserve cures, and so that they don't have lots of suspicious dissapearances, saying that he can wait for quite some time.
Ranma makes better friends with the senshi, although they don't know he's figured out that they are probably the senshi. His tutoring sessions end up changign from with Hinako-sensei to with Ami, who is glad to meet someone who can understand her on an intelectual level, although Ranma's not quite as knogledgeable as her nor does he have the same level of inteligence, but he's closer than most of the senshi, and Ami often comes over with Hotaru, who comes to hang out with Vita.
Happosai has recovered from the magical beating he received, and he finds a scroll to release a horde of demons through a portal into Nerima. The Sailor Scouts and the Knights, and Ranma and the martial artists all work together to stop all the demons, which Sailor Moon banishes, Happosai is drained by the Knights, the Sailor Scouts are enraged with Happosai and see him as an inhuman villain and want to kill him to stop him from ever doing such a thing again, but Hinako defends him, pointing out that if it weren't for Happosai, she'd be dead, and that Happosai does have a good side and doesn't deserve to die, he just is selfish, vengeful, and lacks proper self control. Sailor Moon agrees but gives Happosai a warning that he must behave good from now on or she'd come again and seal him away in another dimension, then she uses her healing magic on him so that his body returns to normal human and he no longer relies on draining energy from women's undergarments and groping women to survive, but on food and water and normal human needs instead, but this exhausts her a surprising amount, since she is no longer connected to the moon, and all the groups retreat.
The Martial Artists are upset at how powerful the Sailor Senshi and the Knights are, and many are afriad of them, especially Colonge and Happosai, who think that the martial artists should train so that they have the power to get rid of the magical people in case they become enemies, Ranma refuses to train under Cologne and Happosai, explaining that he's working on his own training, but is convinced to go to Dr. Tofu for training.
Dr. Tofu has been training Mamoru, and decides to allow Ranma to join in the training. Mamoru is shocked by Ranma's ki blasts, which remind him of his Smoking Bomber attack, and realizes that it's a ki blast as well. He demonstrates the Smoking Bomber, which shocks both Dr. Tofu and Ranma, who are really excited to see that it's a pure ki attack, Ranma begs Mamoru to teach him how to purify his aura and use pure ki attacks, Mamoru doesn't have much knowledge for that, but he explains that Rei knows a lot about spiritual techniques and can help him purify his aura, after which Mamoru will try to teach Ranma the Smoking Bomber.
Ranma is very busy for a while, studying, learning martial arts in the afternoons and magic at night, but his grades have improved tremendously and he's grown a lot stronger.
Ranma finally learns some really weak magic, some basic sheilds, binding, healing magic, and purifies his aura, and learns the Smoking Bomber. At this point, his grades have also improved a lot, and Ranma's behavior has changed for the better thanks to the influence of his mother and some others including Ami, Rei, Mamoru and Dr. Tofu, not to mention making friends with Usagi. The other martial artists, who've gotten a lot stronger, but a lot crazier as well thanks to the tainting techniques and shortcuts Cologne and Happosai have been using, end up getting in a big brawl with and over Ranma, the girls are having their own little brawl over Ranma while Ranma fights strengthend and crazed Ryoga, Mousse, and Kuno.
The fight is rather unfair, since Ranma's rivals are all boosted up with all sorts of permanent magical enhancements Cologne and Happosai have given them, including super soba (the guys only since it increases facial hair), and they've all been taught battle aura techniques that rely on dangerous emotional tainting but give them huge boosts of power, while Ranma has been weakened considerably since he has banned himself from using the self detrimental techniques such as his old battle aura techniques that relied on emotions, the soul of ice, and the amaguriken (which is like the 8 gates of Naruto used by Rock Lee IMO, damaging the body by exceeding it's limits) whereas his rivals have been taught techniques he's banned himself from using and are using dangerous ki blasts, envy from Ryoga, pride from Kuno, and wrath from Mousse.
Ranma knows he can defeat them using magic, but he's losing badly because he doesn't want to reveal the magical power he's gained, he's going all out mostly defensive, but his opponents are all now stronger and faster than he is, and he's outnumbered, and they arent' exactly unskilled, although they aren't as skilled and adaptable as Ranma is when he's going all out. Ranma's about to ask the knights to transform and save him, when the Sailor Scouts interrupt the battle, they are all powered up by having new sentient control items created by Moon, Mercury, and the moon cats and using the powers of the Ginsuzishou.
The Martial Artists, who've been training to defeat these magical potential foes, attack all out, while Sailor Moon and Sailor Saturn bring away a badly wounded Ranma. Sailor Moon attempts to heal Ranma and cure his curse with the Moon Healing Escalation, but the Jusenkyo curse fights back, hurting Ranma in the process. The dragon demon of Jusenkyo, a great ancient spirit who drowned there and cursed the land, manifests, and explains it won't allow Sailor Moon to cure Ranma, but it can't overpower her, so instead, it destroys Ranma's true form, destroys Ranma's spirit and aura, and attaches Ranma's soul and memories into Ranma's remaining girl body, making Ranma into a real girl. Ranma is unconcious during this.
When Ranma awakens in the senshi's place and finds out she's become a real girl, she becomes upset and depressed and blames the senshi in a rage, running away and summoning her magical knights to her. Ranma sets up a fortress with her Magic Knigths and they work to finish the Book of Darkness, Ranma revealing her magical powers and mastering her cat form and making a pure battle aura, they quickly work to finish the book of darkness, planning on getting revenge on Sailor Moon by changing her into a man permanently and restoring Ranma's manhood with the Book of Darkness' full power.
As the attacks increase and the Senshi and the Knights seem about even in power, although the Knights are still making progress thanks to the abundance of weak magic in Ranma's world, Ranma burries herself in the study and practice of magic, because she realizes she'll have to be really powerful to actually defeat Sailor Moon, analyzing the Book of Darkness' codes in great detail, as her body becomes weaker from the drain of the Book of Darkness increasing as it nears completion. The Knights are able to work together to drain all of the power out of Jusenkyo itself and drain all the power out of Saffron in a way that changes him into a normal mortal, and changes the phoenix people all back into normal humans, and absorbs the Keys of Asension into the Book of Darkness to furthur increase it's final power.
Ranma's dreams haunt her of good memories of friendship with the senshi, who the Knights catch one by one in their civilian identities, getting chances to drain each one.
Finally, the book is nearly complete, and the Knights drain Sailor Moon, causing Ranma's final awakening. Unfortunately, even the full power book can't restore Ranma's origional form because it's inherently linked to Ranma's magic. In Ranma's depression over this discovery, and her initial failure to change Sailor Moon into a boy, discovering that Sailor Moon's essence is inherently female and locked and she's impossible to make male down to her soul, whereas normal souls are not male or female, the defense program of the Book of Darkness goes berzerk, sending Ranma into a dreamworld where Ranma has a male body.
While outside the Sailor Senshi are attempting to battle the defense program, which Sailor Mercury and Sailor Mars realize is going to blow and destroy this entire dimension and their own, the very thing they came to stop, the Knights also join in to help them, because they realize Ranma, who they've come to care for, will die as well, and that the codes of honor Ranma taugth them would not allow them to let the defense program kill so many people.
Ranma in the dream, realizes that although she's male in body, she's female in mind, and wakes up and encounters the administration program, and finds out from telepathic contact of what is happening to the defense program outside. Ranma overcomes her depression when Sailor Moon offers to let Ranma come back with them to their world, since Nodoka and Genma had allready been revealed to want female Ranma dead, and that the Knights and Sailor Scouts didn't care wheather Ranma was a boy or a girl, Ranma was still their friend.
With a new determination, Ranma uses her administrative powers to interface with the administration program, and releases the defense program and manifests outside, re-naming the Book of Darkness to the Tome of Sunny Days. The group discovers that they can't destroy the book of darkness's defense program with their current power, but Pluto thinks to transport everyone and it while it's weakened to their home dimension, they weaken the defense program again, and transport it up into outer space, where Sailor Moon uses her full power to destroy it completely.
Afterwards, Ranma gets help from Sailor Moon and Sailor Mercury to re-program the Tome of Sunny Says so that the defense program wouldn't be re-created as a berserker program, and enhanced the book with Silver Millenium technologies, and the Senshi's magic with Velka technologies, finally, Sailor Moon decides to make Ranma a permanent part of the senshi, and uses the Ginsuzishou to link Ranma's soul to the star seed of the sun and make Ranma into Sailor Sol, and re-naming her civilian identity Saotome Koneko, and granting her independence from Sailor Moon's command as a free agent and ally, so that Rama could be immortal and not leave her Knights some day due to old age. Sailor Pluto helps set up Sol and the Cloud Knights to live in her mansion as Ranma finished schooling.
Then of course, comes the final threat that will cause the battles leading up to the great ice...

"Health, Learning & Virtue will ensure your happiness; they will give you a quiet conscience, private esteem & public honor." Thomas Jefferson (1743 - 1826)