>>36622808It's index number in GO is 891 so idiots are thinking that means it's at the end of the Gen 8 Dex. But that's meaningless. Zeraora is 888, for example.
In reality we can 't know for sure whether it's Gen 7 or 8 yet because we don't know if it's actually in anything but GO which was updated for Gen 8 weeks ago (meaning it could be a Manaphy - an unlockable found in a Gen 7 game for a game with Gen 8 present just as Ranger was a Gen 3 game which gave a mythical to the Gen 4 games).
However, for the reasons presented by
>>36622586, it's almost certainly National Dex number 808, not 891.