>>28819541>The only thing canonically established as taking place elsewhere is RSEI agree. Going a step further I think it's better to say, "the only games that canonically take place in different universes from each other are RSE and ORAS," meaning that no matter how we place the other games in the series, we have two timelines.
We have the RSE timeline, in which we know Megas do not exist
And we have the ORAS timeline, in which we know Megas do exist.
So now we have to try to place all remaining games into one of these two timelines, if possible. We'd like to avoid making a third, brand new timeline since I agree with your ideal of keeping things simple.
The remaining games Gens 1 through 5 all lack Mega Evolution, which would place them in the RSE timeline. Furthermore, since they existed long before the notion of alternate universes, I think it makes intuitive sense that all Gen 1-5 games, RSE included, would be in the same universe.
Placing the remaining Gen 1-5 games in the ORAS universe would be more complicated, since it would require retconning Megas as existing in those games, despite never being mentioned, Pokemon native to those regions having Megas, and Megas being widely known and used outside of Kalos in the Mega universe being firmly established in ORAS.
It's true that we don't have evidence in canon either way, but between the two possibilities, placing these games in the RSE timeline is simpler.
It also allows for new remakes to be easily inserted into the timeline if Game Freak so desires.
XY is easier to place, since it does have Megas. It must be in the ORAS universe, because Megas simply cannot be retconned out of XY since they're, well, there.
