Halo L4D Gears of War Alan Wake Chromehounds (too big?) Fable Conker Blinx DOA (they're technically not exclusive but the bulk of the series has primarily been associated with xbox) Ninja Gaiden Blue Dragon Bulletwitch (oh dear god D Crackdown Kameo Lost Odyssey Perfect Dark/zero? Ninety-nine Nights Tenchu Z(fuck yeah!!!) Jet Set Radio Future(double fuck yeah!!!)
it would definitely have to be some sort of projectile/shooter/melee type of fighter. I'd probably prefer it to be in the style of Power Stone or Custom Robo. I'd say it's a plus that it doesn't copy off of SSB's style.