Somebody started a thread on Hydreigon that got me thinking: many of the changes have been bad for it but there is a silver lining. Obviously, the Draco Meteor/Dragon Pulse nerf, the Fairy x4 weakness and the fact that they completely wall its STABs is not good news. But OTOH, most Steels no longer resist Dark and a number of them (Metagross, Bronzong, Jirachi, Aegislash) will take SE damage. Also Hydreigon's movepool is almost endless so it does get Flash Cannon via TM 91 as a way to hit a predicted Fairy switch-in. So maybe it'll adapt and find a niche depending on how the metagame shapes up.