gameshark is for USA and Action Replay is for Europe. So it would be depending on where your games came from if you'd buy an Action Replay or a Gameshark. Unless the games from both regions are 100% identical (which they probably aren't even though ds is region free), I don't think action replay or gameshark would support each others games.
Actually, no. Action Replay has been available in the US for a long time, it just used to be labeled as GameShark, until after GameShark 2 version 2 for PS2. Then Datel started selling the device themselves in this region, and InterAct sold the GameShark brand name to MadCatz. Before that, Pelican's Code Breaker was relly a device called Xploder, from a European company called Blaze. Since then, Code Breaker became its own device as of version 7, and GameShark 2 version 3 and higher are now relabeled Xploder devices. North America is the only region to have all three devices in use. Europe only has Action Replay and Xploder. Japan only has Action Replay. Xploder and Code Breaker, as well as Action Replay 2 version 2 (at least on PS2) can use raw codes. Action Replay MAX/v3 and higher encrypt the codes, and part of what's incryped is a region indicator, and the devices only accept encrypted codes. You can't use European codes on an American Action Replay and vice versa because the device will reject a foreign region code when it detects one encrypted into the code.
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