UNLOCK RABIO OR LEPUS

On the Player Select screen, hold R, and on Controller 2 press:
Left, Down, Right, X, Y, A, B, Left, Down, Right, Down, X, Y, A, B.
This allows you to play as either Rabio or Lepus.



UNLOCK THE BOSS FIGHT MODE

On the Player Select screen, hold R, and on Controller 2 press:
A, Left, Y, Right, X, Down, B, Up
You'll play a version of the game where you fight nothing but the bosses.