Here are some cheats and tips for the game Battletoads In Battlemaniacs.
Extra lives and continues:
Hold Down + A + B before the title screen is displayed. With
those buttons held, press Start at the title screen. The screen
will flash red to confirm correct code entry. The game will begin
with five lives and five continues.
Level select:
Press Up, Down(2), Up, X, B, Y, A at the character selection screen.