I've seen two glitches or perhaps just new game mechanics.
First: fighting moves appear to be super effective against flying pokemon. Perhaps this is because they are mostly part-normal but I've never seen this before this generation.
Second: training my pokemon using Exp. Share and when I go to check on it, its max HP is higher eventhough the HP itself hasn't changed. No i haven't used in battle because its weak. I suppose this could be apart ofthe new ev mechanics but as for now it seems like a glitch.