Level & Difficulty Selection
Select a 1-Player or 2-Player game, then hold A or B and press Start to begin game play. Alternatively, hold A + B and power on the NES. Continue to hold those buttons and press Start twice.

Continue Game Play
Hold A + B immediately after the Game Over Screen appears.

Options
Press Select + Start + B at the player number selection screen. Press Up or Down to select an option, press A to change the current option, and press Start to begin game play.