What's up with those places like Gamefaqs that allow you to download DS Game gamesaves? And how do they work?
Basically, some people like to protect their original copies of the game. Flashcarts like the R4, M3 Simply etc. are capable of storing nds files, or essentially the actual backup. These can boot the backup with no need for the original, thus protecting them. However, in order to save, when the game tries to do this, the data is stored on a .sav file (on the memory card in your cart). People can then plug these into their computer and access the .sav file (save), thus meaning people are able to get very far on a game, and then distribute the .sav file for other flashcart users to use. Hope this helps!