

The third type of DS flashcarts still uses slot-1. Because of its popularity, there are a lot of DS flashcarts using that name, so pay attention to what you buy. They are slot-1 flashcart which can run DS ROMs and are colloquially know as "R4" by some, which is actually the name of a particular slot-1 flashcart that became popular. These are also the most cheaper and easy to find. This and the other hassles of slot-2 flashcarts such as ROM patching and save batteries means this kind of cart is not particularly attractive.

You will also need additional setup to use a slot-2 flashcart in DS mode such as flashed firmware, which already requires a DS mode flashcart to install. Slot-2 flashcarts may have problems with newer games, since they got substituted by slot-1 flashcarts. These flashcarts are old, but may be good, particularly if you want to also use them on a GBA or to play GBA ROMs natively on a DS/DSL. The first type works with the slot-2 (which makes it incompatible with DSis and 3DSes, since those lack it). To run homebrew or ROMs on your Nintendo DS you'll need a flashcart.
