For DS, maybe, but look at the old flash carts for GBC and so on, those were one game at a time. Those loaders have to be written like homebrew would.
You must not have owned the DSTWO long enough to notice. It used to have constant updates that changed what title it shows as. It's been pretty stable for a while, since their newest exploit loads from a file on the MicroSD card, so they can just update that if Nintendo blocks it. I'm not 100$ sure how their exploit works, but I'm guessing the current game it shows up as is white-listed (you know, so people who own the retail copy can play it), and the Supercard team just changes tiny details about the cart if it gets blocked (like, say, the serial number? I dunno)