Enter the following as a name, then press L2 + Circle + Square to activate it:

PUPPETS	All characters:
ALLRAYMANM	All levels
ALLFISH	All battle levels
ALLTRIBES	All race levels
FIELDS	All mode 1 levels:
ARENAS	All mode 1 battle levels
TRACKS	All mode 1 race levels
CARNIVAL	All skins
OLDTV	Old movie-style screen:
3DVISION	3D mode

Thanks to Revolution readers Ryan Greene and Chewy!