Alright, here is what I support atm (plus a few things of my own).
->S Jirachi is really, really good right now. It is a really versatile threat and does a lot for its team. ScarfRachi is incredibly annoying, as it can outspeed a lot of Pokemon and a decently powerful Iron Head with a 60% flinch chance is an incredible revenge killing tool and allows Jirachi to revenge a lot of Pokemon. It can also run a defensive set with Wish and Paraflinch so it can be rather annoying and it provides tons of nice support. It also has other annoying tricks up its sleeve, like SubToxic and Superrachi. With all these, Jirachi can be slotted onto any team and also be very unpredictable and annoying in every match, definitely an S Rank mon, it's very threatening and requires every team to carry at least two checks to it.
->S Hydreigon is a monster. It is a scary wallbreaker with a Life Orb, as LO boosted Draco Meteors sting and put massive holes into any Pokemon that doesn't resist or is immune to Draco Meteor. It also has incredible coverage with Dark Pulse, Fire Blast, and either Superpower or Iron Tail to smash Blissey or Florges/Aroma, Hydreigon is a scary wallbreaker. It can also run Scarf to be a decent revenge killer still against offense, as it has a powerful Draco Meteor to hurt a lot of faster Pokemon. Even better is its typing and ability, which give Hydreigon a good set of resistances to come in on and force switches with. It can come in on threats like Krookodile, Shaymin, and Raikou, which only sweetens the deal to using this thing. Definitely an S Rank Pokemon.
->S Suicune is pretty great right now, especially with Slowbro gone. Suicune is literally the greatest bulky sweeper. CroCune is incredible right now, as Suicine's impressive bulk means it has an easy time nabbing a lot of CM boosts, and it is a very durable Pokemon on both sides, while RestTalk and Pressure make it even more annoying. Suicune sets up on a lot, and after a number of CM boosts, Suicune's Scald will sting quite a bit, not to mention that lovely burn chance. A very good Pokemon that is a very high level threat, so much that it'll take something like a Grass or Electric type moves to take it down.
->A- Machamp is good. Guts Machamp is very scary, and its Close Combat hits super freaking hard, plus coverage in Knock Off and Stone Edge give it some real sting. Bullet Punch is okay priority too. It can easily take advantage of status and do a lot of damage. No Guard DynamicPunch is also still as fun as ever, and a strong DynamicPunch with a 100% confuse rate is annoying and not easy to switch into. It also has passable bulk, unlike Mienshao, Infernape, and Lucario, which is cool, and unlike Cobalion and Virizion this thing hits hard right off the bat. Only problem is it has a little competition and is quite slow, but it's a very threatening Pokemon nonetheless.
->A- No competition from Victini means these two can really shine. And honestly, Entei and Darmanitan are monsters. Entei has a powerful Sacred Fire with a high burn chance which makes it quite fearsome, and very few things can reliably switch into it, those can can endure a Sacred Fire risk getting burned, which makes Entei quite a fearsome Pokemon especially with a CB. ExtremeSpeed is also awesome priority which allows Entei to serve as a nice revenge killer against frailer Pokemon like Mienshao. Darmanitan has incredible power behind its Flare Blitz, and with a Life Orb that Flare Blitz steamrolls through everything that isn't named Alomomola, Suicune, or Swampert. Superpower, Rock Slide, and U-turn are all nice bonuses, the latter being useful to nab momentum. Scarf is also great and allows Darmanitan to perform fantastically against offense.
->B Goodra is a very good offensive support Pokemon, C is an embarrassment to it and its capabilities. Goodra can take on quite a few Pokemon in this meta like Chandelure, Blastoise, Ampharos (takes Dragon Pulse by virtue of that stupid bulk), Nidos, Shaymin, Roserade, and Raikou. Heck, it can even function as an emergency Hydreigon check if the dire need arises. It has a wide offensive movepool and solid offensive presence to use, so it can always give a punch back in return after sponging hits from several Pokemon. It has two awesome abilities, Sap Sipper is nice to switch into Seed Flare (something not many Pokemon can lay claim to), Sleep Powder, etc. Gooey is also awesome to drop Speed of physical attackers, which is clutch. Not being able to heal itself kind of sucks, and it's sort of weak, but it's a pretty good mon nonetheless.
->B+ Yeah agreeing with King UU. These three are good and have solid niches but are not that splashable, they do require being slotted into a specific team to work well, plus they have their own issues. He explained it quite well so I won't reiterate.
->At least C (maybe higher) Yeah this thing is definitely viable. SD is a pretty good set, and Kabutops can sweep pretty decently with a +2 Aqua Jet and a Stone Edge that hits hard. It has a nice typing to come in on Flare Blitzes from Darmanitan and Brave Bird from Crobat, among others, and Weak Armor is a clutch ability. It's a nice sweeper overall. It can also use Rapid Spin which is pretty cool, it kinda does meh against Sableye, but it owns Chandelure, and it's one of the few offensive spinners in UU other than Mega Blastoise. Idk where it should be but it definitely deserves a ranking.
Blissey is okay where it is btw, it's a nice special wall but it's really passive and doesn't really fit onto every team. The fact that it's just sitting there just kinda kills it and somewhat limits its use.
Long wall of text but whatever lol.