Gradius 3 And 4: Mythology Of Revival

					
Full Double Shot PowerUp
Pause gameplay and press Up Up Down Down Left Right Left Right Square Triangle. You can only do this a couple times.
Full Laser Shot PowerUp
Pause gameplay and press Up Up Down Down Left Right Left Right X Circle. You can only do this a couple times.
Gradius/Salamander
To play first stage of Gradius and Salamander, play Gradius III until you get to the final boss who tried to shoot 3 spread electric balls at you. Don't dodge them, touch the middle ball to wrap into Gradius world or touch the lower one to wrap into Salamander world. Once you've entered one of them you can play them again by going to Extra Mode in you menu and selected the world you desire.
GameShark Codes