Note: This game is also titled Star Gladiator 2: Nightmare Of Blisten.

Play as Kaede:
Highlight Rain at the character selection screen. Then, press Down, Down, Left, Left, Up.

Play as Rai-On:
Highlight Byakko at the character selection screen. Then, press Up, Down, Left, Left, Right, Left, Up.

Play as Evil Gamof:
Highlight Gamof at the character selection screen. Then hold Start and press A.

GameShark Codes

Low Health P2      F8B985D300000000
 
50% Health P2      F8BA85D3C0705038
                   F8B985D300000064
 
Infinite Power P1  E327095D00000090
 
No Power P1        E327095D00000000
 
Infinite Health P2 F8B985D3000000C8

 
Infinite Health P1 51E76400000000C8
 
Low Health P1      51E7640000000000
 
50% Health P1      51E46400C0705038
                   51E7640000000064
 

   
 

Thanks to Revolution reader Suzy!