My old boss used to be a game dev, and many people at is company used an unofficial DS emulator (I believe No$GBA but could be wrong) quite extensively for debu

My old boss used to be a game dev, and many people at is company used an unofficial DS emulator (I believe No$GBA but could be wrong) quite extensively for debugging/development purposes. They even paid the developer several thousand dollars so that they would improve the debugger function. This was all unofficial, of course - Nintendo had no idea and would not have been happy if they found out.