Reset the NES three times during the title screen, then press Up(2), Down(2), Up, Down, B, A on controller two.

Intentionally lose the game and wait until the title screen appears after the game over screen. Then, press Up(2), Down(2), Up, Down, B, A, Start on controller one, then press B on controller two. Press Up or Down to select an new level, then press B on controller two to begin game play.