Hope You Enjoy.

These work on the sony psp only.

Level select
Select two player mode, then enter hg? as your initials. Return to the main menu
and start a single player game. At the world selection screen, hold L + R and
press Select to unlock all levels. To lock all levels, hold L + R and press Select
again.

Unlock bonus stages
Place first on all high score boards for all stages in a world to unlock bonus stages
for that world.