Cheat: Costumes

Xtreme Costumes:
Unlocked at the main menu by entering: Up, Up, Right, Left, Down, Down, Start

Additional Costumes:
Beat the game to unlock the following costumes: Colussus without metal, Colussus 90's, Original Beast, Bobby Drake Original Iceman, Street Clothes Magma, Original Nightcrawler, Original Jean Grey Phoenix B, Wolverine 90's Weapon X, Original Cyclops Cyclops 80's, Storm's white outfit