I used to do spider hacks on awakening to edit skills and classes, I also added Lucina, Robin, and Ike on my Jap Fates through hex editing.Yeah, you have to edit Gamedata.bin in a hex editor multiple times, so it's not something anyone could easily pick up and do. Though if you're comfortable in a hex editor it's very quick and easy.
Do I need anything special or just the hex editor and the gamedata.bin? I read Deathchaos' trick but it was a bit confusing, he used tools I don't knkw where to get, except for hxd.
If only there's a way to get it to work on Gateway haha