Unlock Boss Characters:
 
Beat the game with at least four characters to unlock
the bosses one by one. 


Unlock Character Comic Pix in Cerebro Mode:
 
Beat 10 rounds with any character in Survival Mode
while in their normal costume to unlock their Comic
Pix in Cerebro Mode.


Unlock the 3rd Costumes for each character:
 
Graduate the Acadamy with straight A's with any
character to unlock their third costume which you
choose by selecting them with the O button.