I'll just quickly give my VR since I've been meaning to do it for a while now.
S
Tauros
Snorlax
Chansey
I'm not going to split these up. I think they're all very important in their own ways and all contribute to the success of a team in different ways. Since offense can (and sometimes wants) to drop Chansey, I'll put it at the bottom, but don't look into that too much.
A1
Starmie
Exeggutor
I'm putting Mie over Egg, because I feel like Mie complements more play styles while being able to be better through the entirety of the game. It also works as a better glue mon. Egg is still very strong and those who don't think it's at least top 6 are crazy imo. It has Sleep, Boom, Tankiness, Stun Spore and can hit fairly hard.
A2
Alakazam
Zam is still a really great mon that can just pop off and do stupid things. That being said, It's no as consistent or as durable as Mie and Egg, and it has much less utility. This is enough to put in a sub rank below this.
A3
Rhydon
I know this is where I'm getting controversial. For me, Rhydon is still an A mon, but Zap is no longer. Zap has serious competition from Jolt nowadays and struggles against Jolt itself. Meanwhile, Rhydon is still going along and benefits from there being less Egg. It just cancelling Electric mons is also too big to overlook imo. It still deserves its A Ranking, and although I understand where everyone is coming from by putting it in B. I'm going to politely disagree and say it's better than that.
B1
Zapdos
Jynx
Zapdos and Jynx are two very solid Pokemon, but just quite aren't up to the A rank. Zapdos has unfortunately lost some of its former glory. Rest Jolt has made it harder as it has another Pokemon to worry about having a less than ideal match against. Less Egg and more Mie also gives Jolteon more of an advantage nowadays. That being said, it's still one of the best Pokemon in the tier and is still the best Electric-type imo. It's probably the best late game mon, after Tauros, and I don't want to undersell it.
Jynx has also proven itself to be the best sleep lead. Jynx + Mie teams have definitely completely reshaped the meta compared to 3 years ago. Jynx has also had an impact on Big 4 teams, because it's just is a good lead.
B2
Cloyster
I'm putting Cloyster into its own subrank. I think it's really good and one of the best mons in the tier, and it needs to be a step above the other B ranks. However, I don't think it's quite as good as Zap and Jynx. Maybe I'm underselling Cloy or overselling Zap/Jynx, but this is how I feel at the time of writing.
B3
Jolteon
Slowbro
These are like the solid B rank mons. (I guess B on the non-numerical list) Looking at Jolt, things have changed a lot with it.
Rest Jolteon made a huge impact on the meta, and it's no longer a somewhat niche Poke. It even has a legitimate place alongside Zapdos now. Some people do rate Jolt higher, and honestly I understand why. However, Zapdos hits so much harder, is a bit more consistent.
Slowbro is a Pokemon that goes up and down with usage. It's crazy how we keep doing the same thing over and over. People like Slowbro and it gets used a lot; people oversell it in their minds; people feel it was overrated and wonder why its OU; Slowbro creeps back up into the meta. This is like 2nd or 3rd time I've seen this happen. It's not always going to be some sweeping god (although it can be from time to time), but it is a solid Pokemon with good utility and can make an impact in a game thanks to its bulk and T Wave.
B4
Gengar
This is where the more niche, but still good, Pokemon end up imo. Gengar is the peak of that concept. It's got some use as the fastest sleep lead with T Bolt and Boom. However, it doesn't really have a solid place in the meta. There's absolutely strats that can only work with Gar though and it is a solid Pokemon when it's needed. But that's not very often.
B5
Lapras
Yes, I'm keeping Lapras in B. It's still a solid mon with some really solid traits. Use it as a Cloyster that gets Thunderbolt, Body Slam and Sing. That niche almost never comes in, but it's there. I also think some Double Ice teams (underrated team btw) appreciate Lap. Lapras and Cloy really step on each other's toes and unfortunately and the meta isn't really big enough for the two of them. But regardless of who is in charge now, I think that the other still viable enough to stay OU.
C1
Articuno
Persian
These Pokemon are really good, but aren't quite OU.
I don't think Articuno is an OU mon personally. It's realy good when it works, but until it can find a better footing in the meta (maybe double or triple ice teams) I just can't see it as more than the best non-OU mon.
As for Persian, I'm a player who knows a game can be won or lost in the late game, regardless if you screwed up the mid or early game. In that crunch time, Persian makes a solid offensive mon that can really swing the game in your favor. Tauros + Persian can be better than Tauros + Zap in some games, and it really can't be underestimated. Persian's techs are also criminally underrated and I think people are sleeping on Persian a bit.
C2
Dragonite
Moltres
Dragonite is kind of a stupid mon, because AgiliWrap is a stupid combination. OU handles it well enough which is why it only has a solid niche, instead of being a full blown threat.
Moltres also gets APT, which can also make it stupid. But it's limited to Fire Spin (which sucks way more than Wrap). Moltres is really here because it's a good anti-physical mon. When Chansey and Starmie are dead, Moltres can come in and win the game. Generally, I'd rather use Zapdos. But Moltres does get APT and a burnt Tauros or Don is pretty much as good as KO, barring crits.
C3
Victreebel
Golem
To be honest, these mons can be solid in a game when you need their strats. However, their strats are really too niche to make use of in normal gameplay.
I don't think Victreebel is still an OU mon personally. It has a great MU against slow teams, but those fled the meta along with Vic's hopes and aspirations. I think it should be dropped back down to UU, personally, as it's no longer able to serve its role outside of some Wrap teams and as specific counter teaming. Which makes it not a true OU mon in my eyes.
I'm still a fan of Golem. honestly. It's not as good as Rhydon, so it has to find its own niche as boom support with Electric immunity. However, it does the role well. It's need rarely comes up and that's why its low in the C Ranks. However, it's good when needed and can do well.
D1
Hypno
Sandslah
Kabutops
Porygon
Kingler
Except for Hypno, these are Pokemon that can work in even the highest level of play, but are really niche and need a specific team built around them.
I feel Hypno has becomes a lost and forgotten Pokemon. It has legitimate use as paralyzer and sleeper that isn't weak to Blizz, but it never gets considered anymore. I think people need to start remembering that it can fit on teams. Hypno honestly might be a C Ranked mon, we just don't give it enough love/don't consider it to be the legit threat that it is.
Sandslash, Kabutops and Kingler are all SD users. However, Slash works outside that role and work with Sub as well, and Kabutops works as a IceLax wall. Slash and Tops.
Porygon is something that is really hard to use well. It takes on Lax well and pretty much nothing else. It needs some very specific strategies that can work, but I really haven't seen Porygon do amazing unless the opponent didn't really know what to do against it. I may even be overratting it honestly.
D2
Pinsir
Kangaskhan
Flareon
These are good. They just doesn't have the niche or strats established, like the D1 mons.
D3
Poliwrath
+4 Poliwrath 2HKOes everything with Blizzard, Hydro Pump and Submission. If you're not worried about Egg, you can also run Hypnosis instead of Blizzard. Wrath is inconsistent, which is why it's down here, but it can pop off and sweep, and is not something to underestimate for sure.
D4
Venusaur
Machamp
Raichu
These are probably the last three notable mons, which can work from time to time. They're hard to pull off and have some really bad matchups, but the can be used in high level play.
E1
Hitmonlee
Raticate
Tentacruel
Omastar
Gyarados
Clefable
Nidoqueen
Even harder to pull off than the D4 Ranked mons, they can still win games and you're not going 5v6 by using them. If a really good player is using one, I'd take it as a serious threat.
E2
Dodrio
Dodrio can work in high level games, but it needs the right match-up and the wrong one is playing 5v6.
Written in a rush and on my phone. Sorry for any mistakes.