Entering Codes
Insert the Action Replay disk into the GameCube. A few seconds after starting up your GameCube, the Action Replay menu will appear. Eject the disk and insert the "Shadow the Hedgehog" game disk. The cheats menu for "Shadow the Hedgehog" will appear.
New codes are entered by selecting the "Enter New Cheat" choice at the top of the cheats menu. A keyboard will appear on the screen to allow you to enter codes. The master code for "Shadow the Hedgehog" must be entered first. It is KP35-TDC3-N9RYW-U8MF-AYPY-3RJBY.
Infinite Supplies
You can give Shadow an infinite supply of rings, lives and ammo for his adventures.
The code for infinite rings is MEAX-VKGF-NVBFE-1HKQ-VNVR-X7MN1.
The code for infinite lives is F1Q5-6H8C-HY202-M5C5-K0H4-FHX5Y.
The code for infinite ammo is XMXA-2VKC-CBUZU-ARJM-7WXE-1QKQ1.
Earning A's
An Action Replay cheat makes earning A ranks on missions much easier. In most cases, an A rank for the mission is earned by running straight through the mission after entering the code.
The code for a maximum main score is DNC3-Y6E0-KJVFF-HCDX-5CUM-WRKHH.
Fill Hero and Dark Meters
The Hero and Dark meters in "Shadow the Hedgehog" need to be full in order to use Shadow's special abilities. These meters normally fill quite slowly, but there are two Action Replay cheats that let you fill them whenever you wish.
The Hero meter is filled by pressing the Z+R buttons. The code for the Hero meter is KZ5T-8W3F-318YT-MY8X-60GD-HTGYK-PGZR-U7MK-VH6G1.
The Dark meter is filled by pressing the Z+L buttons. The code for the Dark meter is UMCX-P155-UM6K7-KETR-W0JH-EPRMM-1N9F-TNKR-3KN7V.