This game is also available on GBC.
Up + L
Ice
Up + X
Dungeon
Up + Y
Spinal
Up + R
Orchid
Up + B
Cinder
Up + A
Thunder
Down + L
Riptor
Down + Y
Eyedol
Down + X
Street
Down + R
Sabrewulf
Down + B
Fulgore
Down + A
Secret Sky
Down + B simultaneously on controllers one and two.
Random
Up + Start
Select practice mode opponent:
Use controller two to enter practice mode. Select a character and press Start(2) to return to the title screen. Use controller one to enter practice mode to fight the character that was chosen using controller two.