Xiaolin Showdown Codes -

Alternate costumes:
Earn the indicated rank to unlock the corresponding costume.

Warrior: Martial Artist rank 
Monk Costume: Monk rank 
Robot Costume: Wudai rank. 
Street Costume: Grass Hopper rank 

Play as Chase:
Defeat Mala Mala Jong in the last level in Adventure mode.

Play as Jack:
Defeat the Jack Spicer Robot at the half-way point in Adventure mode.