>>58965853The gen 3 games are easily some of the most malleable, this is why so many ROMhacks exist for them but beyond that the gen 3 games have the ability through the platform they are on to inject custom software to directly interface with the game. This is how Box (which effectively does the same exact thing that HOME does, only offline) and Colosseum/Gale of Darkness made it work during that actual gen. And someone else did say this too, but they obvious got something like this working for gen 3 to gen 4 transferring.
I genuinely think it would be as easy as having the code on the HOME app itself to look for FireRed/LeafGreen data, then just write to the ROM as you move things in/take things out. Not to mention they could also use HOME to do other, cooler things, too.