The two cents of a nobody on the rankings:
Suicune -> top of A+. He's good, but I don't think this guy has seen top five usage at any time in the entire history of advance. Really dangerous with either the offensive or defensive set messing up most teams but not really as splashable as the other S-tiers or even something like Swampert. Also has nowhere near the versatility of Tyranitar/Gengar/Celebi who have like ten very different viable/common sets each vs. the maybe four from Suicune which are basically either offensive cm or defensive rest.
Jirachi -> middle of A. Curselax is hard to use in the current meta of Sand Spikes spam but I've seen it win more games than CM+Wish, SubCM, or CM+3 Jirachi. Astarachi and Utility Lax are pretty comparable though and each have strengths and weaknesses. Blissey while not as versatile is the single hardest counter that exists in the game. Aerodactyl can always flinch his way to a victory. In my experience, these three in particular have won a lot more games either offensively or defensively than any Jirachi variant, and are equal at worst.
Zapdos -> below Blissey. Decent mon, but offensive sets get walled by too many things and the defensive sets really aren't the same without sleep talk. Rest variants get forced into sleep cycles by pretty much everything and while you're asleep you're giving free switches to dangerous stuff like Aerodactyl. Feels so bad when the opponent switches in Skarmory on your rest turn and then spikes in Zapdos' face. Baton Pass is cool though.
Jolteon -> B+. This guy takes so much from the things it's supposed to check (Suicune/Gengar/Zapdos etc.) whether it be status or a 70% hydro pump. On the offensive sand teams he's usually on, if the opponent manages to set up a layer of spikes, which is virtually guaranteed with SpDef Skarmory, his longevity is laughable. Good for keeping momentum and spikes down though.
Flygon -> B+. Don't see why he is above Milotic. Decent rock resist but requires quite a bit of support (Magneton/Pursuit) if you want to land toxic or do anything meaningful with earthquake. Even then, he still has 4MSS. Defensively, he only covers Tyranitar and Electrics without HP Ice or Toxic, which is virtually none of them nowadays.
Raikou -> bottom of B. Absolutely the worst OU. The only thing he's good for is checking if the opponent has Blissey, and even then they sometimes send out Celebi instead. Really shaky answer to the stuff he's supposed to come in on (Gengar/Zapdos). Like Jolteon, really suffers from high toxic Skarmory and will-o-wisp Gengar usage. Still not as bad as some are making him out to be.
Claydol -> B+. Refresh variant is the most reliable defensive spinner in the tier. Combined with Magneton you basically guarantee winning the spike war. Poor offenses make him niche but he absolutely has better team matchups than things like P2 and Gyarados.
Cloyster -> B+. Similar to Claydol, really good in the current meta, but nonetheless very matchup reliant. Almost never spins but can easily get 3 layers vs mag teams. Usually gets pretty relevant booms if it doesn't die to toxic and sand first.
Kingdra -> somewhere in the Cs. Outclassed pretty hard by Suicune and Ludicolo and there are at least 10 things in the Cs better than this.
Venusaur -> B. Have a hard time putting this over anything in 1U except maybe Raikou. Has good matchups with some speed against almost all common leads except Salamence. Significantly less stable than Celebi, and getting hit by any status is devastating. Doesn't take more than half from any non-stab special attack, but every mon has something that can hit Venusaur for a third, which combined with spikes, sand, and no recovery makes you wonder if sleep powder was worth it.
