Oh, ROMhacks that make it a hack, like Light Platinum, Flora Sky, Ash Grey, etc. ARE allowed? I took the wording "main series game" to mean they were NOT allowed, but hacked versions of the actual games were allowed. I have no idea that patched ROMs to create other games are allowed.
Either way, he's also not through that game's E4 yet. Isn't this a post-game challenge?