I think that of my movesets for Food Fight so far:
M&Ms > Ronald > Chester
I feel Ronald's potential was squandered a little by my aim for a shoto archetype (though I don't regret that decision either, necessary evil) while I wasn't really paying good attention to Chester's archetypes (he's a stance fighter) while making the moveset and didn't lean hard enough into the extreme sports Poochie angle. Red and Yellow on the other hand, I feel everything clicked for - a decent reference/hammerspace-to-regular-attack ratio, a well thought out gimmick that was considered for all moves, a good grasp of the duo's personalities, so on. It's funny too, because the concept for Red & Yellow's gameplay was something I've considered before in the context of multiple characters in multiple games - hypothetical and real - but always dismissed, however once I started thinking about how Red and Yellow could be implimented the climber + slapstick concept kinda clicked for me.
In all seriousness, though, I do think character gimmicks aren't inherently bad and there are some instances in which they are warranted (such as Hero's MP and Steve's plethora of sillyness), but some of them just feel forced, and some of the character gimmicks I've seen for fan proposals just make the character seem clunky as all hell.