Alternative Costumes
Press up and X whilst selecting your character to get an alternative costume.
Codes
Select sub bosses:
t=triangle.s=square

Kahn:up,up,down,down,t
Stygian:left,right,left,right,t
Redemtor:up,down,left,right,o
Juni:up,left,left,up,s
Mongwan:Down,down,down,up,t
Vodu:left,left,left,up,o
Bimorphia:right,right,right,down,s
Moloch:up,right,down,left,s

Youll hear a metal clang again if this worked