I wanted to give my thoughts on some of the nominations brought up, since I've had some time to play lately, and have been following uupl as well. Also, I was going to make this in iambic pentameter, but this already took way too fucking long to make lol.
Latias absolutely belongs in S. Z Moves really push it from a top tier mon, into borderline oppressive. Scarf Krook is good, don't get me wrong, but Lati is absolutely a large reason behind it's very high usage. The fact that it's so versatile, having access to not only multiple viable Z moves, but also plenty of different sets, from Specs, to Calm Mind, to Roost + 3 Attacks, and even the basic defog set, which I don't run anymore because I think the other sets are better, but it's still a decent enough set. It's typing is also pretty solid defensively, being a good switch in to Keldeo, provided it doesn't click icy wind, and also resisting common types including Water, Grass, Psychic, and Fighting. And thanks to its very good special bulk, and respectable physical bulk, Latias can almost always take at least on hit. Hell, if it Calm Monds on the Clefable switch, it can set up on and beat Clef, which is pretty hilarious imo. Pursuit isn't a garunteed counterplay either, since it needs to be chipped down before it gets killed if it decides to stay in, especially against Aero. Latias is honestly pretty stupid, easy to just slap onto any team, and it's rare for it to not do something in a match, and I think it belongs in S
Nidoking should definitely rise. I personally would like it in A-, but at the very least it should rise to B+. The amount of teams that have no switch ins is insane, and depending on the fourth slot, it can pick whether it wants to bust through Snorlax and Blissey, set up rock, use taunt or sub, or even use Sucker Punch to take out Lati if it really wants to (I've used it, it's not a bad option at all). Of course, being able to take advantage of any Clefable lacking Knock Off or Psychich, which to be fair are legitimate options, particularly knock off, is amazing for it. It's honestly better than all of the stuff in B+ imo, and should at least be there. Hogg explained why this should rise better than I could, so look to his post for more explanation.
Blastoise belongs in A-. This thing can nearly 1v1 the entire tier, thanks to its power and the fact that only STAB super effective moves have any chance of actually taking it down in one hit. It's a good spinner, since the viable spin blockers are all scared of switching into this thing, although hazards do unfortunately wear it down, although Blastoise does beat nearly every viable hazard setter. Honestly, if it wasn't for the fact that it takes up a Mega slot, I'd nominate it to like A+ lol. Really good in this meta, I just started using it and I've been really liking it.
As an avid user of Starmie, I do advise everyone to at least try out offensive Rapid Spin, defensive is just ass imo, that set alone is like B rank if anything, I would much rather use Tentacruel. I'm not opposed to a drop, in fact it probably should honestly, but offensive Starmie can be such a menace to switch into. Analytic allows it to really pressure things that try to switch into it, like Latias and Primarina, since even if the Starmie user chooses the "wrong" move, it still does a fair amount of damage, being able to potentially put Latias and Primarina in range of Ice Beam and Psyshock, respectively. Combined with its excellent coverage, and the fact that none of the tier's common pursuit trappers will ever want to switch into this thing, makes Starmie a real prick to switch into for most teams. Obviously, offensive Starmie is not exactly easy to fit on a team, only really fitting on more offensive teams, but the fact that as a spinner it doesn't really forfeit momentum that like Tentacruel or god forbid Forretress, and doesn't take up a Meag Slot, makes it one of offense's best hazard removers imo, especially since unlike Lati it doesn't remove hazards from the opponent's side. It does suffer from 4mss, really wishing it could fit Hydro, Tbolt, Ice Beam, HP Fire, Rapid Spin, and Psyshock on one set, but of course the opponent has to guess what coverage it's running, since Hyrdo is really the only move that really necessary, since Starmie is still effective even without Rapid Spin. I've drones on long enough, so in summary, defensive is bad, offensive is pretty good, I personally oppose a drop, but honestly I would not lose any sleep if it did drop, since I can totally see why someone would want to to drop, so I really don't care where this thing ends up lol. Just don't talk about defensive, since I will fully admit that that set flat out sucks.
Don't really have much to add about Venomoth, Dodmen already covered it, I just started using it, and this thing is fucking awesome, it's been serving me really well. It's way to good for the C ranks imo.
Also, for the rest that I don't have much to say about, or don't feel like expanding on lol
Krook rise to A+
Gliscor rise to A
Gengar stays at A-
Snorlax rise to B-
No comment of Persian, I have literally never used one myself lol
Indifferent about Magneton
Terrakion to A/A+ (I'll need a little more experience facing experienced players using it to really decide, but I feel like upper A ranks is a good ballpark for now)
Arcanine should drop to C, possibly C-, it's ass
Volcanion should drop to B+