Deo-A with follow me/fakeout support essentially makes it a 6 turn game as it KOs everything one-by-one. Yea, your support mon could go down, they could have a faster fakeout or they could use spread moves, but Deo-A beasts.
I've actually used support Genesect to some success with screens, t wave and normal gem explosion. Speaking of which, explosion is incredibly underrated.
Shaymin-S needs to be out at the right times. It isn't like Cresselia or Suicune who just sits there the whole match and tanks. It can come in after some paralysis has been set up to paraflinch or it can come in on water and/or ground types and DESTROY.
Sewa, Darkrai doesn't have to use Hypnosis. I've used Nasty Plot+Focus Blast+Dark Pulse+Snarl. When partnered with an intimidater, Darkrai is almost like a bulky sweeper. This is only one that can completely run through teams with Fake Out/Follow Me support.
Just throwing out my opinions on these Pokemon that people find to be 'underwhelimg'. They all can perform very well, they just come in and spam attacks without regard like a lot of the highly used ones.
Oh also, I kind of want to see the percentage of Tyranitar that use Protect. That has gotten me a lot of free turns when they start aiming Close Combats and Hydro Pumps at your weather starter.
Edit: "Acrobatics in Aerodactyl would be heaven sent, but you can try the odd ball Power Herb/Sky Attack. I cannot say I fully recommend it on this format because you can pull it off better in VGC where matches are shorter and the potential OHKO from Sky Attack comes much more handy. Of course Aerodactyl doesn't stay alive that long either. Sad thing is, it probably doesn't OHKO Hitmontop after Intimidate."
Focus Sash Sandstorm Aerodactyl survives surprisingly long and helps against weather spam. Idk if Sky Attack OHKOs top, but it might considering it usually doesn't run 252 Def. Some even run speed over HP.