If you're talking about DS games, you would need to buy a flashcart (e.g, DSTWO or Acekard 2i) first. Once you got a flashcart, move the game files (.nds) to the MicroSD card. You will have to flash the flashcarts first, though and that can only be performed on a DS system. There is no way to play backups of 3DS games. Also, Cosmo Black looks the best.