Gradius 3 and 4: Mythology Of Revival Codes -

Unlock instant double shot power-up:
After passing the first boss, pause your game, and push , , , , , , , , , . You will hear a sound if you have entered the code correctly. You can only do this 25 times (amount of levels in the game) If you want to power-up for player two, push , , , , , , , , , , Select, Start.
 

Unlock instant laser shot power-up:
After passing the first boss, pause your game, and push , , , , , , , , , . A sound will confirm correct code entry. You can do this up to 25 times. If you want to power-up for player two, press , , , , , , , , , , , .