Yes , but why?I think pretty much all flashcards are compatible with almost every game. Although everyone here would recommend you the R4i Gold. Before you buy it, did you hack your consoles yet?
If they weren't, I'd tell you to wait, a new exploit's on its way and it uses NDS flashcard, but we don't know which ones/if it'll support all flashcards, so it'd be better if you waited for the list/exploit to be released and then buy a compatible flashcard. But both 3DSes are hacked, so buy the R4i Gold. Just make sure it's not from http://r4isdhc.com/Yes , but why?