Looking for flashcart for 2DS

Its been years since I touched a flashcart. But a friend just bought a 2DS (the flat one, not the model with the clamshell hinge) and he wants me to help him out.
Just looking to play DS games (not 3DS games), will most any card work? Like R4i Gold, etc..
Is the card dependent on the firmware version of the 2DS?