One thing I kind of want them to do is ban legacy moves. Almost no one wants Pokemon Bank gone. If that'd happened then it would be up there as one of the reasons why Generation 8 is the worst generation yatta yatta as part of the "this new generation is suddenly the worst generation" trend, pissing off millions of Pokemon fans across the world. So what I think GameFreak should do is keep a legacy move ban. If your transferred Pokemon has a legacy move, it can't be used in online multiplayer until it's removed as part of the meta-game. Some exceptions I believe are tutor moves of the previous generation. Due to this, I believe this not only a great way for transfer Pokemon dating back to 3rd generation to play fair game with others but I also believe due to this, that transferred Pokemon should be fully allowed in all rating battles and VGC tournaments rather than just be kept back to free battles and special-types of tournaments. I can't be the only one who's annoyed by the fact that I catch all these Pokemon from previous generations only to find out later you can't use them in any of the multiplayer formats except free battle and specific tournaments. As for abilities, I really don't think that matters much as GameFreak is only just going to make them most, if not all, abilities legal sooner or later like tutor moves.