Since there a few cards can play 3ds games on 3ds xl and 3ds xl now, this post will tell you all about them.
Currently there are three cards can play 3ds games on 3ds and 3ds xl console. they are gateway 3ds, r4i gold 3ds Deluxe Edition and 3dslink. All of them can play 3ds games on the 3ds and 3ds xl console, but only working on V4.1-V4.5 3ds console.
So if you want to buy a flashcart to play 3ds games on your 3ds or 3ds xl, at first, make sure your 3ds console firmware is between V4.1 and V4.5, so you can use any of them, if your 3ds firmware is higher than V4.5, currently there is no way to play 3ds games on it with a flashcart.
gateway 3ds card is the first card that support 3ds games, and the other two were just released last week, all of them have the same features. the R4i Gold 3DS Deluxe Edition and 3dslink prices are cheaper than gateway 3ds card since they are the clones of gateway 3ds card.
So for now, if you want to play ds games on your 3ds xl or 3ds console recommend you buy r4i gold 3ds this one: R4i Gold 3DS Wood R4i 3DS flashcard For DS DSi 3DS, 3ds xl
if you want to play 3ds games on your 3ds or 3ds xl, and your 3ds firmware is lower then V4.5 , then you can buy r4i gold 3ds Deluxe Edition , this one: R4i Gold 3DS Deluxe Edition to play 3ds games on 3ds xl and 3ds console