At the Title screen, hold L1 + R1 and enter the following cheats:

Play as Nicole:
Left, Up, Down, Up, , Up.

Hyper punch mode:
Left, Right, , Up, , Right, Left.

Unlimited canteen:
Left, , , Down, , , ,

Original Pitfall:
Circle, , Left, Right, , , , Up, Circle. You can find it at the New Game screen.

Original Pitfall 2:
Left, Right, Left, Right, , , . You can find it at the New Game screen.

Thanks to Revolution readers Harry and june!