Enter the following at the title screen for the desired effect.

Effect	Code
Choose up to twenty Players	B, A, Right, Right, A.
Level Select	C, A, Right, Left, Right, Up, Left, A, Right.
Unknown	B, A, Down, B, A, Down, B, A, Down, B, A Down.
Unknown	A, B, Right, A, C, A, Down, A, B, Right, A.