>>19116457It doesn't mess the timeline up, so much as it's just inconvenient.
It doesn't really benefit the plot, it just means theres gonna be an NPC somewhere that says you can trade pokemon through time and space, rather than just space.
It would honestly have been better if X/Y was happening at the same time as FR/LG, or if OR/AS were sequels, but we gotta' take what we can get I guess.