Jersey Devil

99 lives:
Press Triangle, X, Triangle, Square, Square, Circle during game play.

Extra lives:
Jump on the fountain at the start of the game and ride the water stream to the top to collect the bonus life. Press Start to pause game play and press Square to display the status screen. Then, press Circle to resume the game play. Collect the same bonus life, which will re-appear. Repeat this procedure to collect an unlimited number of lives.