Can 3DS games only be on the Nintendo 3DS?

if you want to play 3ds games on the nintendo 3DS, yeah, you need to buy the 3ds games. if you want to play ds games on the nintendo 3ds, just buy a flashcart instead, there are many flash cards that let you play ds games on the nintendo 3ds, i recommend you buy r4i gold 3ds from r4ids.cn or dstwo card, do not buy other clone cards.