There are things called NoPasses, such as the Passcard 3rd generation(what I use because I don't want to flash.). The M3 is your best bet. At least in my eyes. Great GBA and NDS support, fun stuff. Go with whatever you want. If you have a Compact Flash Card, go with M3 CF. Secure Digital card? M3 SD. Mini SD? M3 Mini SD.
Good luck.
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