The following are known Action Replay Codes for Gradius III and IV on Sony Playstation 2 (PS2). These codes were also known as GameShark Codes and in most cases will work on both devices.

Device Compatibility: Action Replay & GameShark (Version 1 & 2)

Master Code – Must Be On
EC878D78 1433BDF8

P1 – Inf. Lives
4D97937A 1456D7A5

P1 – Mega Shield
4D97A096 1456E70C

Speed Select: Press L1
0C1E5B6A 1456AC0C
4D97938E 1456E7A6

Missile Select: Press L2
0C1E5B6A 1456B10C
4D97938E 1456E7A7

Double Select: Press R1
0C1E5B6A 1456B80C
4D97938E 1456E7A8

Laser Select: Press R2
0C1E5B6A 1456B20C
4D97938E 1456E7A1

Option Select: Press L1+L2
0C1E5B6A 1456AD0C
4D97938E 1456E7A2

? Select: Press R1+R2
0C1E5B6A 1456BA0C
4D97938E 1456E7A3

! Select: Press L1+R1
0C1E5B6A 1456B40C
4D97938E 1456E7A4

Infinite Lives
3C20E330 1456E7A8

Insane Score
1C20E32C 17E9C70C

Power Ship
DC918328 14CD4667
4C20E266 1456EBA2
4C20E268 1456EBA5
4C20E27C 1456E79D