If you're struggling try entering the following codes during the game to activate the correspondng effect.

Doubles Enemy Reflex Points
Press X, X, Square, Square, Triangle, Triangle, Circle, Circle, Triangle, Triangle, X, X, R3.

Undying (lose health but never die):
Press Square, X, X, Square, Triangle, Triangle, Square, Circle, Circle, Square, R3.

Infinite Rage:
Press Triangle, Square, Square, Triangle, Circle, Circle, X, X, Triangle, R3.

During gameplay press X, Square, Circle, X, Triangle, X, Triangle, X, Square, Circle, Circle, Square, R3 to get the yellow and blue costume which Wolverine originally wore when he first joined the X-Men. If you have entered the code correctly the costume will be available for selection at the 'Main' menu.