That I'm not too sure about, because I know that many DS flashcarts use different ones. Most though seem to work with any kind of flashcart. Just be careful because older flashcarts don't support SDHC micro sd cards. the most important thing is getting the right flashcart, which is probably the DSTwo for emulating GBA ROMs. And I would also double check your 3DS firmware, because I believe flashcarts are updated to continue working with new firmwares, but just double check it works with the current 3DS firmware, better safe than sorry.