Go to 'Extras' at the 'Main' menu and select the 'Cheats' option and enter one of the following codes to enable the corresponding effect.
Unlock ALL Costumes:
Enter Right, Left, Down, Up, Right.
Unlock Invincibility in Story Mode:
Enter Down, Down, Right, Up, Left.
Unlock Infinite Chi:
Enter Down, Right, Left, Up, Down.
Unlock Full Upgrades:
Enter Left, Right, Down, Left, Up.
Unlock 4x Damage Multiplier:
Enter Up, Down, Up, Right, Left.
Unlock Big Heads in Story Mode:
Enter Down, Up, Left, Right, Right.
Unlock ALL Multiplayer Maps:
Enter Up, Up, Left, Down, Down.
Unlock ALL Multiplayer Characters:
Enter Left, Down, Left, Right, Down.
Unlock Dragon Warrior Costume in Multiplayer Mode:
Enter Left, Down, Right, Left, Up.