Unlock BJ Penn:
At the main menu, press L1, R1, L2, R2, R2, L2, R1, L1, Triangle, Square,
Square, Triangle, Start.

Unlock Shaq:
At the main menu, press Right, Up, Left, Right, Down, Left, Up, Right, Down,
Left, Square, Triangle, Triangle, Square, Start

Unlock Mask, Skyscrape & Punkass:
At the main menu, press Down, Down, Up, Right, Left, Down, Back, Start.

Shop for Free:
Get enough points to buy the item you want. Press X to select the item and then
choose "Yes". Do not press X, instead press Circle to return to the Shop menu.
You will now have your item and all your points intact.