Pause the game, hold L2 and enter the following:

Invincibility:
Right, Right, Left, Right, Left, Left, Right, Left, L1, Up, Up, Down, Down, Up, Down, Up, Down, L1.

99.9% charge:
R2, R2, Left, Right, Up, Down, Right, Left, Up, Down, Triangle.

Full blue power, missiles, and bits:
R2, R2, Left, Right, Up, Down, Right, Left, Up, Down, Circle.

Full red power, missiles, and bits:
R2, R2, Left, Right, Up, Down, Right, Left, Up, Down, Square.

Full yellow power, missiles, and bits:
R2, R2, Left, Right, Up, Down, Right, Left, Up, Down, X.

Bonus Ships:
Enter the following as passwords at R's Museum:

• 5270 0725 - Lady Love ship (#3)
  
• 2078 0278 - Strider ship (#24)
  
• 1026 2001 - Mr. Heli ship (#59)
  
• 1009 9201 - Curtain Call ship (#100)

Thanks to Revolution reader Bill Myers!