Roserade and Alakazam get HUGE buffs in their Special movepools due to Aggrons/Rhyperior's strangely large special movepools. Roserade could run a LO or Scarf set with Leaf Storm / Ice Beam / Earth Power / Rest | Fire Blast, while Alakazam has a really fun moveset, which includes Fire Blast, Ice Beam, Thunder, and Surf. Aggron and Rhyperior don't gain anything that make them OU worthy.
Speaking of huge movepool buffs, Raikou has a HUGE buff to its movepool. It can also run Aura Sphere without having a silly nature, although an expert belt / LO set of Thunderbolt / U-Turn / Ice Beam / Flamethrower has immense coverage, and has other options such as Aura Sphere, Weather Ball (needs shitty nature if chosen, but can be used in a Rain set), Roost, Nasty Plot, Giga Drain (although it's only useful for certain things), Scald (On a Rain CM set, Scald could be amazing. CM / Scald / Thunderbolt / Substitute | Roost), Stealth Rock, Tailwind, Trick, and many more. I chose U-Turn over Volt Switch for the same reasons Thundy-T uses U-Turn over Volt Switch - isn't blockable and destroys Celebi while damaging Lati@s more than Volt Switch would, although they don't like taking an Ice Beam. Mew gains access to Weather Ball and Volt Switch, which is nice, but doesn't get much outside of that.
While not that much more threatening, Keldeo does get access to Ice Beam and Fusion Flare from Kyurem, the former being more useful than the latter (Fusion Flare only hits Celebi and gives more insurance vs Ferro. Also gives it PseudoSTAB if Sun is summoned, which is nice). Roost could be useful on a CM set, but Scarf/Specs is probably still better. It also gets Signal Beam, which is very similar to HP Bug + HP Ice but better in every way. What's important though is that Kyurem and Kyurem-W gets Calm Mind while Kyurem-B gets Close Combat and Aqua Jet. Kyu-B know has a decent movepool physically (Fusion Bolt / Close Combat / Outrage / Aqua Jet | Dragon Claw is decent enough).
Jirachi gets Dragon Dance, V-Create, Earthquake, and ExtremeSpeed. Jirachi's new toys are simply fantastic, and make it even more versatile than it was before. Is it DD? Or is it SubCM? Maybe it's Scarf? Specially Defensive is also a thing. Choice Band is semi-viable now, since unlike Victini, Jirachi isn't weak to Rocks.
Brongzong looks like a huge boost to Stall teams. Roost and Sleep Powder make Bronzong a pretty good stall mon, adding its great defenses and levitate. If you wanted to be silly, you could run a bulky QD set, which is better than the CM set it could run before.
I wonder how Carnivine could do. It has Shell Smash now, but it's speed is a low 46. Still, it's movepool is decent enough, both physically and specially. It's probably outclassed by another Shell Smasher or sweeper though, but this could be its chance to be somewhat useful.
Aerodactyl gets U-Turn and Spikes, which is pretty nice. Spikes probably won't see much play on Aero sadly, except maybe in HO teams. U-Turn, however, is really nice for scouting purposes. It also gets Encore if I'm not mistaken, which is really cool. As a silly option, it can use Guard Swap, although this is probably gimmicky at best.
Shuckle gets Leech Seed. Don't fuckle with the Shuckle.