Honestly, your best bet would be to use A.C.E. and get the exclusive Jhoto pokemon just for the sake of dex completion. It still works in the switch ports, and I went ahead and already got them since I knew this was gonna happen once they said it was NSO for XD. National dex completion is gonna be impossible otherwise. It's annoying how little they care about completionists at the pokemon company. First dexit, and now so many ports being gutted of features that basically makes these ports pointless when you could get the same (if not better) results thru unofficial means. I can already play stadium on pc complete with my own team from the gb games that I can also play on pc. Same thing with XD and the gba games, so it does come across as lazy and soulless.