>>28822898The Mega universe sets itself apart by being the only one with the great war of Kalos, AZ's weapons, and the subsequent mega evolution of Rayquaza and presumably many other Pokemon. Rayquaza is different in that it mega evolves after it eats meteorites that were most likely irradiated by AZ's Weapon. This universe sets itself apart by of course megas, but also the fairy type, the removal of the GTS in favor of the PSS, etc. This universe will most likely be the one we reside in until a further critical change takes place.
The events of a Mega/Primal influenced Kanto ( think Origins/Generations type of deal) = ORAS > The events of a Mega/Primal influenced Johto = The events of a Mega/Primal inspired Sinnoh > The events of a Mega/Primal influenced Unova > The second events of a Mega/Primal influenced Unova = XY >=? Sun and Moon
So in summary 3 different universe, one distinct timeline. For example, Blue Oak is a characters, every Blue Oak says "Smell Ya Later", but the Blue Oak encountered in Red Version is a different Blue Oak than the one that was said to have visited Kalos in XY. The events all happen fairly the same ( ORAS and RSE all involve Team Aqua and Magma and have basically the same story yet what transpires is all slightly different in each version) , but they are influenced by the universe they take place in. So someone can talk about Team Plasma in XY but it's not the same Plasma from the non mega Universe. We can very well witness these unseen events upon future remakes.