Spokavriel wrote: Constrained by design and not pilot sounds like allot of design isues will come up making it so Ranma could get frustrated by the Mech not keeping up with his skills because it was optimized but still couldn't be as versatile as he is use to fighting.
Adapting to the situation seems to be something you can't always design for and could end up a liability.
Well it's like this:
Anything that isn't fuel and disposable ordinance is dead weight. The more dead weight you have the harder it is for your craft to maneuver and get up to speed. On a Mech dead weight is going to be largely the armor and robot parts, although things like RADAR will also be a factor. In other words you can make a light frame that'd really be able to turn and burn like no other, but it'd be the last Mech you'd want to put in a boxing match. On the opposite side one could make a mecha that would be king in physical strength and armor, but would no be particularly maneuverable all things being equal.
You also have to size your engine to fuel load and endurance. The bigger your engine the more thrust you can produce, but the more fuel it must consume. Note that fuel and combat ordinance do impact performance. There are significant differences related to wing loadings on real aircraft, which is why you'll almost never see those advertisized max loadouts in practice.
You can also use high quality control and lots of routine maintenance as a tradeoff to allow you to push the piece of equipment to operate at the limits of what's feasible. Or in other words you can design your parts to fail quicker allowing lighter parts and higher performance, but these as a consequence need to be routinely replaced. Any craft down for maintenance isn't up to fight, and is a very real consideration. As is the pure raw logistics costs.
The only way you're not on the same playing field with your choice of design trade offs is if you have a significant technological advantage. Or if we weren't talking machines a significant advantage in capabilities on all opponents. That kind of thing happens like Alexander the Greats modifications to the Phalanx with much longer spears, but tends to get adapted to fairly quickly in the great scheme of things. About the only way it can't involves the side with the technological advantage also having such an extreme military and economic advantage it can really just curb stomp whoever it wants if it really wanted to.
"Good at everythings" as a general rule suck at everything. The F-111 debacle whose only saving grace was it could take a reasonable payload a long ways being a relatively recent example. The F-18 and F-35 which could be argued in a similar light have the power and maneuverability, but are lacking in terms of range or endurance, making them poorly suited for missions fulfilled by aircraft such as the A-10 Thunderbolt II aka Warthog and S-3 Viking, which are top in their fields of Close Air Support and Anti-Submarine Warfare respectively.
I personally find it ironic you're arguing Ranma's flexible and adaptable, while simultaneously arguing he needs a significant unfair advantage in all parameters to be "flexible and adaptable." Kind of a complete and utter vote of no confidence on what you're advocating. Especially as one can always select the equipment to be used for a strike package a whole lot easier then they can overhaul their physique.