now that i think about it, you are very right! every cartridge-based nintendo system got a flashcart.
Hell, it goes beyond Nintendo, Everdrive alone has done a good job of providing most old systems with a flashcard of some sort: NES, Master System, SNES, Genesis, TurboGrafx-16, N64, GB(C), Game Gear, GBA
Then of course you have a billion different R4 flashcards for the DS, the 3DS has a few with the most notable being Gateway, and even the Vita has the Cobra Black Fin. Even the Atari 2600 has one called Harmony Flash Cart.
I'm sure there are a few much less popular cartridge-based systems that never got such a device, but it seems apparent that if your system is cartridge based, it likely can have some sort of flashcart. Seems the only factor is really going to come down to the security of the system, hence why seemingly any old cartridge-based system could have a flashcart made for it if there is enough interest in such a device to get the likes of Everdrive to make one. Hell, I bet the Pokemon mini could have a flashcart made for it if anyone actually cared about having such a thing.
Edit: Nevermind my hypothetical there, there actually already are a bunch of freaking Pokemon Mini flashcards: http://www.pokemon-mini.net/flash-carts/
Last edited by duffmmann,