Single player normal mode alter ego:
Press Up(2), Down(2), Left, Right, Left, Right, B, A at the title screen.

Single player mania mode alter ego:
Press Up(2), Down(2), Left, Right, Left, Right, B(2) at the title screen.

Versus mode alter ego:
Press Up(2), Down(2), Left, Right, Left, Right, A, B at the title screen.

Versus mania mode alter ego:
Press Up(2), Down(2), Left, Right, Left, Right, A(2) at the title screen.

Player vs. player mode:
Press Up(2), Down(2), Left, Right, Left, Right, A, B at the title screen. A sound and the phrase "Command On" will appear to confirm correct code entry.