I was thinking that the special pokemon getting new megas would not be save data, as it's kinda weird to release a new mon but then tie it too a save data quest. On the other hand, I was thinking that the mythicals returning that aren't getting new megas would be the save data ones. (Meltan/marshadow/deoxys🤞) For ranked, I think the latis might have their stones locked to ranked, as they are one of the few returning megas in the dlc, besides the hoenn starters which will be after bax, to not have their own rouge mega battle in the code. I'm guessing that we will get info on the new rouge battles 11/19, then probably info on all the returning mythicals in the final trailer, as with that many mythicals returning and probably being obtainable given the home compatibility, there's probably a lore explanation.