In the second level, go to the room with a Jabba the Hut hologram and Guybrush Threepwood statues. Destroy the three machines in the room and the Holocron for the costume will appear from the Jabba hologram.
Unlock the following costumes by performing the corresponding tasks:
COSTUME - HOW TO UNLOCK Experimental Jedi Costume - Complete the game with "Light Side" Ending Saber Guard Costume - Silver Medal in Cloning Spire Trial The Dark Apprentice's Robes - Complete the game with "Dark Side" Ending Tie Flightsuit - Complete "Kamino The Escape"
To unlock secondary light saber crystals, complete each of the first ten challenges with at least a gold medal. Also, new cinematics will be unlocked with bronze medals in the challenges.