Level select: 
     Press L1, L2, L1, L2, L3, R1, R2, R1, R2, R3 at the title screen.

Invicibility:
     Press Right, Left, L3, R3, Left, Right, R3, L3 while playing.

Unlock Pumkin Jack and Santa Jack coustumes:
     Press Down, Up, Right, Left, L3, R3 while playing.

Thespian Jack costume:
     Get an "A" rank on all levels.

Phantom Jack costume:
     Get an "S" rank on all levels and complete both secret chapters.

Dancing Jack costume:
     Successfully complete the game.

PJs Jack costume:
     Successfully complete the game.

Pumpkin King costume:
     Defeat the spider Boss.

Santa Jack costume:
     Defeat the Doctor.