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.