Play as Nicole
Hold L+R then hit LEFT, UP, DOWN, UP, B, UP, UP.
Bottomless canteen
Hold L+R then hit LEFT, X, B, DOWN, X, A, X, B.
Hyper Punch Mode
Hold L+R then hit LEFT, RIGHT, B, UP, B, RIGHT, LEFT.
Unlock original Pitfall
Hold L+R then hit B, B, LEFT, RIGHT, B, X, A, UP, B.