Greetings to thee, Touya. As you may or may not have been able to guess, I am contacting you regarding recent interest in facing off against eachother in a Pokémon-related fightin game... While I can't do so immediately, I will brobably be available in, say... three hours from now. Is that good for you, or is it the middle of the night there or something along those lines?
The main thing I run with in this case is that RSE are the games canon to XY's place in the timeline, and at the very least, that was true prior to the reveal of Oras - simple, I know, but they reinterpreted and rewrote the script in order to make sure Mega Evolution and the Kalos region fit seamlessly into their story. The old script wouldn't have worked unless they wanted to intentionally shoehorn Mega Evolution in - and they wouldn't do that with its story importance to XY, now would they?
Really, I guess I was just trying to make a huge case out of my *personal* belief. My thought, while it is crazy to believe, is that the remake regions are their own timeline, and they allow setup for continuity nods back to themselves in future remake regions. I'm thinking so far forward because, eventually, SOMETHING will make a nod or two to it...
By all means, though, I do NOT believe in the "Megaverse" where XY and Oras are separated from every other game in the series. That thought is just weird.
So to finish off this comment, I have to ask a question that I'm fairly sure I asked before. Do any of the games released so far make reference to features only present in remakes, like the Sevii Islands?