While at the title screen, press X, Right, A, Y, Left, B, L + R.

Evolve Energy Item

While at the title screen, press Y, Right, Down, B, L, A, R, A, Y.

One-Hit Kills

While at the title screen, press Right, Up, Left, Down, A, L + R.

Unlock Additional Characters

Beat each character in Single Player Mode to unlock them.