110-hit combo
At the character selection screen, choose Cable, Gambit, and B.B Hood. You will have to unlock B.B Hood and Gambit by buying them in the Secret Factor. During arcade mode, get up to at least to level 3 or higher. When you do, press L1 + L2 and all three of them will do their Hyper Combo specials. This combo will do at least 110 hits and a lot of damage. It works better when you are close to your opponent.