Marvel vs. Capcom Cheats

To play as Onslaught, successfully defeat each of the secret characters in arcade mode, saving then to a memory card. Once all the secret characters have been enabled, the Onslaught mode will open up on the the title screen, enabling player 1 to play Onslaught either with a second player or the CPU.

After you win the match and are in your victory stance, press START to gain control your character and perform moves. NOTE: You can not do this if you have KOed your opponent while both of your characters are on the screen

After you win a match and your character does his/her victory pose, press Start. You'll be able to attack your fallen opponent while he/she is down.