Heal
While in battle, press X and triangle at the same time. Your player will say something like"Specil Delivery"and your player will be healed, but just by a little bit. It's usefull, but doesn't help much!

Master code
Press Select, Down, R2, L1, R1, L2 at the main title screen. All features, including alternate costumes, outro FMV sequences, behind the scenes movie pictures, the Pool Party, and Psylocke, Juggernaut, Spider-Man, and Professor X will be unlocked. To use Spider-Man, highlight Cyclops and hold L1 at the character selection screen. To use Professor X, highlight Magneto and hold L1 at the character selection screen.

Juggernaut
Successfully complete the game using all default characters and Psylocke in arcade mode.

Professor Xavier
Successfully complete the game as Juggernaut. Then, highlight Magneto and hold L1 at the character selection screen.

Spider-Man
Fight in arcade mode until you face Spider-Man. Defeat him and finish arcade mode. Then, highlight Cyclops and hold L1 at the character selection screen.

Psylocke
Successfully complete the game as Wolverine in arcade mode.