Pause the game and press Triangle, Triangle, Right, Left, Right, Left, Down, Left. If you did it right you'll hear a sound. Enter the code again to resume mortality.

At the title screen, press Square 5 times, Triangle 7 times, and Circle 3 times.

Pause the game and enter Up, Up, Down, Down, Down, L, R, L, R, Right, Left. You should hear a noise and when you unpause you'll have maximum power (not counting your shields).

In a two-player game this code will power-up your partner as well. If you use this code with the original Parodius as well and you get a shield when you do it.

If you're maxed out on Options (four rabbits) you can change their alignment by getting enough capsules to choose Options again.