I've been wondering to ask if there is a way to get a different firmware rather than original? Because most games are incompatible.Would the DSTwo firmware work on the N5? I've seen it's possible to run GBA games on that.Sorry for a stupid question.
No, you cannot ever play GBA games from a normal DS flashcard.
The DStwo is able to do this thanks to its onboard CPU and RAM.
Nor can you run the Supercards OS and firmware on it.
You could try a hacked version of WoodR4 but I highly doubt you succeed.
Sorry lad, it's time to buy either a proper flashcard (DSTwo) or a R4i Gold (I think the .cn version is the proper one)