Is it possible at all to play GBA roms on a DS flash cart?

As in, Leaf Green on DS. Or do I have to buy a GBA flash cart?

You need to purchase a Slot 2 flashcart, like the EZFlash 3 in 1. Or have a DS Flashcart specially designed to run GBA games. Supercard DSTwo can, but not perfectly. iPlayer can as well, but cannot play NDS games on it.There are numerous topics on this, so I will lock this one now. Search the forums for the other topics if you want more detailed information.