off the top of my head, would love to see more Smash chars incorporated i.e. Marth, Sheik, Ice Climber, Falco, Doc, Ganon. Very biased but that's the series I grew up with. would not mind more wrestling/puro adaptions either, shameful as it is to admit lol. for something off the wall, maybe Sena from Eyeshield 21?
I'm always interested to find ones even I hadn't thought of, though (I haven't been exposed to many games including fighting yet), so I'm glad to see this thread.