Cel Damage

Go to the character selection screen, select "Load" then enter the following
names as code:

Unlock - all Movies: Emter "MULTIPLEX!"
Unlock all cars, tracks, and modes except plastic mode: Enter "PITA"
Unlock all cars, tracks, modes and plastic mode: Enter "SUSIE!"
Unlock Brian The Brain and Space world: Enter "BRAINSALAD"
Unlock Count Earl and Transylvania world: Enter "EARLSPLACE"
Unlock Hazard weapons: Enter "HAZARDOUS"
Unlock Melee weapons: Enter "MELEEDEATH"
Unlock Movement power-ups: Enter "MOVEITNOW"
Unlock Pencil graphics: Enter "PENCILS"
Unlock Personal weapons: Enter "UNIQUEWPNS"
Unlock Ranged weapons: Enter "GUNSMOKE!"
Unlock T. Wrecks and Jungle world: Enter "TWRECKSPAD"
Unlock Whack Angus and Desert world: Enter "WHACKLAND"

Plastic graphics: Enter "FANPLASTIC"
Go to Smack Attack/Event Settings/Options/Rendering Modes option.
Change this option to "Render: Plastic". Repeat the process, but choose
the cartoon renderer option to return to normal mode.

Unlock additional movies:
Finish Smack Attack, Gate Relay, and Flag Relay with each character

Big head mode: During game play, hold L + R + Up.