>>38127625Megas were a brand new mechanic and essentially new mons themselves. Kalos also had an overwhelming presence of old mons and Megas got tons of spotlight in the games.The game literally gives you a Kanto starter and a Lucario quite early in. It's pretty rare for someone to run a pure gen 6 team in XY.
And need I mention ORAS? XY was literally defunct by the time they got to Ash-Greninja. The stubbornness of only depicting gen 6 doesn't even make sense from a marketing perspective.