Still possible if he is able to backup/restore a save file. His Pokemon wouldn't be edited if that were the case. Because the game creates the Pokemon with no external influence there's nothing fishy about the code, even the stuff you can't see. Maybe worth discussing in the RNG thread if you want more information, as this conversation has the potential to derail this one :)
You are right on that one. If he had save backups it would be perfectly possible. I have a few backup saves myself, but he has a stock 3DS. No CFW, no HB, nothing. Pure, simple, "virgin" 3DS. :D
Anyway, I'll try to look more into it and see if I find something. Thanks again, man.