At the Main Menu, select "Extras" > "Cheats", then activate the following cheats by entering the corresponding codes:

CHEAT FUNCTION - CHEAT CODE
Invincibility in Story mode - DOWN, DOWN, RIGHT, UP, LEFT as a code.
All multi-player characters - LEFT, DOWN, LEFT, RIGHT, DOWN as a code.
All multi-player maps - UP, UP, LEFT, DOWN, DOWN as a code.
Unlimited Chi - DOWN, RIGHT, LEFT, UP, DOWN as a code.
4x damage multiplier - UP, DOWN, UP, RIGHT, LEFT as a code.
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Big heads in Story mode - DOWN, UP, LEFT, RIGHT, RIGHT as a code.
Dragon Warrior costume in multi-player mode - LEFT, DOWN, RIGHT, LEFT, UP as a code.
All costumes - RIGHT, LEFT, DOWN, UP, RIGHT as a code.
Full UPgrades - LEFT, RIGHT, DOWN, LEFT, UP as a code.