ORAS is part of Gen 6, technically, Khoru didn't say just Kalos.
But WHEN were alternate universes brought up?
Zinnia in the Delta Episode
She theorizes that the machine to teleport the meteorite away from crashing into Hoenn would end up in another Hoenn, one without Mega evolution(which using Mega Ray was her plan in the first place)
And since this is a game, every single detail is inportant so it's clear that this would be true
It is a reboot but they only added the Megas into canon
The series now has two main timelines
FRLG and E-->HGSS and Pt-->BW-->B2W2
ORAS-->XY(though the equivalent of the other games in this timeline still happen as there's still mentions of them)
Other games like RBGY(not RWBY), GSC, RS and DP can still technically be canon due to the whole alternate universe but they can't connect into any of the main two(i.e. Cynthia mentions the Distortion world in BW, Steven makes mention of Emerald's events and tge remakes were made to overwrite the originals in the first place)