Get Liquid metal Mode
Go to the main menu and press B, Y, X, B, Y, X.

Get Big Head Mode
Go to the main menu and press R, R, L, R.

Pick Level
Go to the main menu and press X, Y, Z, Z, X, Y, Z, Z.

Enemies Punched Are Set On Fire
Go to the main menu and press B, Y, L, L.

Bullets Explode
Go to the main menu and press L, R, Z, Y, B.

Be Invincible
Go to the main menu and press L, R, L, R, L, R, L, R.

Make Enemies Slower
Go to the main menu and press B, X, Y, Z, L, R.

Tiny Heads Mode
Go to the main menu and press L, L, R, L.