Magearna back to A+
Gonna echo LL on this one because set-up Magearna sets are back and proving that they are still very dangerous. He already talked about Magearna's versatility
here, so I'll try and avoid repeating that. Calm Mind with or without SG has shown that Magearna is capable of taking care of bulkier teams after wearing down its few switch ins, most of which don't have recovery outside of Leftovers or Leech Seed (Heatran, Ferro, Celesteela, Magnezone). Toxapex and Chansey are still around, but +1 Thunderbolt is able to pressure Toxapex pretty well (especially if rocks and/or spikes are up), and then Chansey has to worry about Calm Mind + Pain Split, which puts in mad work against bulkier teams.
It also helps that a lot of bulky offense teams use some form of Grass-type (Tang/Bulu/Ferro) / Heatran or another steel / Lando or another ground + 3 others, with the remaining 3 usually being offensive mons like Greninja, Mega Mawile or Mega Zam. In terms of setting up, Magearna can set up against a Bulu that's not at +2 Atk, EQ users while Grassy Terrain is up and/or if you have a Shuca Berry (Lando, Mega Latios, Tyranitar, Tangrowth, Gliscor), Torn-T (especially if you get Magearna in as they Defog), Ash Ninja locked into Dark Pulse or Spikes, or while forcing out foes that are unable to KO you back or are in range of being KO'd).
Finally, going off of the last point from the previous paragraph, Magearna's natural bulk usually feels underestimated because when you consider how Grassy Terrain from Bulu, intimidate users like Lando and Mawile, and then Shuca Berry, besides Fire types like Heatran, Volcarona and Zard Y, it's actually kind of hard to 1HKO this thing. Revenge killing it after it has set up isn't easy either, because it resists Extremespeed, Quick Attack (Pinsir), Sucker Punch, and then it's usually capable of tanking Water Shuriken from Ash Ninja. Scarf Lando being the most common choice scarf user means Magearna is most likely outspeeding everything after a Shift Gear barring Scarf Kartana or Excadrill in Sand (both of which aren't super common). Then there's also the fact that whatever you do plan on revenge killing Magearna with has to not only be able to tank a hit from a +1 Magearna in some cases, but also be able to KO back.
I have some replays from OLT to prove how Magearna's able to set up and apply a ton of pressure:
https://replay.pokemonshowdown.com/smogtours-gen7ou-396486
Starting from around Turn 20, once Clefable was able to set up rocks, Magearna was able to set up while forcing out Tapu Bulu and then thanks to the Z move, it hit +1 SpA quickly. From there, you can see how because of Fleur Cannon, Mawile was forced to go in to revenge kill Magearna, but because of Magearna's bulk, was unable to do so, and from there Magearna continued to snowball until it missed.
https://replay.pokemonshowdown.com/smogtours-gen7ou-397450
Starting as early as Turn 5, you can see how Calm Mind Magearna was able to apply a ton of pressure to a team that had multiple answers in Toxapex, Celesteela, Excadrill and Reuniclus (Z Fleur Cannon beats Reuniclus, but outside of that, Reuniclus is able to manage Magearna as it did here). After 1 Calm Mind, switching into a Magearna with Thunderbolt + Fleur Cannon wasn't easy and generally speaking, besides Reuniclus and Celesteela, most mons will have to deal with chip from hazards in addition to taking damage from Magearna itself, which makes switching into it a lot more difficult. If you want the specific turn numbers, here you go: 5-8, 19-21, 33-36, and 44-48 (Reuniclus won either way since the Magearna wasn't Z Fleur Cannon, but you can still see how ridiculously hard it hits without it).
Edit: Got one more thanks to The Hallows
https://replay.pokemonshowdown.com/smogtours-gen7ou-395746
Magearna was able to provide defensive utility while helping out offensively without Calm Mind, and then was able to set up against Torn-T for a late game sweep.
Tangrowth to A+
Besides Magearna, Tangrowth is probably one mon that could also go up. Tangrowth and Bulu both have advantages that the other doesn't have, and for Tangrowth, that includes being a more reliable Zygarde answer, having better longevity thanks to regenerator (has to worry less about hazards), being able to switch in and force out Celesteela with Knock Off, act as a better Kartana answer, and in some cases it is able to force out Mega Zam. Bulu on the other hand has more offensive pressure, provides a Dark resist, and provides Grassy terrain, which can be really helpful for mons like Heatran, Mawile and Magearna. In terms of defensive utility, outside of tanking Dark type attacks mainly from Ash Greninja, Tangrowth does a better job with tanking hits and having regenerator to heal off. Bulu can be prone to being worn down by switching in + hazards, and is usually forced to use Protect just to heal up sometimes, but Tangrowth can switch in, force something out, and heal up with regenerator without worrying too much about chip/residual damage. It's kind of hard to say, but I don't feel like one is worse than the other by the degree of a whole subrank because despite being very similar, they both have different advantages that are valuable to any team.
Toxapex: A+—> A+
I feel pex is losing a bit of its luster in this psychic infested meta that also has ground types better than ever as zyg is zyg and drill has picked back up a bit. Also, with what it checks seeming to drop in use while things it coulda checked before like kart have adapted for it. Good mon and i hate fighting it, but A is fair imo.
I don't wanna make this post too long, but I disagree with a Toxapex drop. The combination of Toxic/Toxic Spikes + Scald can actually be hard to deal with, especially for Defog mons, including Torn-T, Scarf Lando-T, Zapdos, Koko, Fini and basically everything except Gliscor. Scald burns and poison from toxic spikes or toxic can help wear down or cripple whatever attempts to switch in, and again, unless you have Gliscor, or Taunt Torn-T, it's not easy to click Defog/Rapid Spin in front of a Toxapex. Ash Ninja is still really common, and as mentioned earlier with Tangrowth, the advantage of having regenerator helps a lot when having to deal with hazard stack because it helps them from getting worn down as quickly as most other mons would. Even if you pack multiple mons that can KO it, if you're unable to bring them in safely, then you're not getting off that easy against it.
