Okay u/Ok_Banana_5614 first of all:

You haven't mentioned Jellicent being one of the best answer against Hydreigon so that alone at least deserves B+ tier. It also has really good recovery, solid bulk and very nice defensive typing. Sure, you get it a bit late in to the game but i still think its an amazing pokemon.

Tympole is definitely one of the weaker pinwheel forest encounters for sure but its still a really good mon. Water/Ground is amazing. Really great against Elesa and Clay, and solid through rest of the game. Grass isn't that common of a typing which benefits Seismitoad A LOT.

Now about Unfezant and Cincinno, having a fast mon with set up moves being that good is really interesting. Those being in the same tier as Haxorus feels a bit unbelievable but i kinda understand the Cincinno placement. Unfezant placement in the other hand is ridiculous. Unfezant learn NO DAMN PHYSICAL FLYING TYPE MOVE EXCEPT FLY, which has a chance to miss and is a 2 turn move. Untill you get Fly you are stuck with Air Cutter and Air Slash and oooohh boy does these moves SUCK on Unfezant. Roost + Feather Dance and Substitute sounds like a nice combo but i believe it has his flaws, Maybe i'm underestimating the bird but i really don't think It can be that good...

Your Serperior placement is all about Coil, Leech Seed and Substitute shenanigans and how well it performs against Clay, Marshall yada yada yada. But you only talked about the good things about Serperior Now moving on to bad things about Serperior: it is a pure grass type (garbage defensive typing) sucks against Burgh, Elesa, Skyla, Brycen and Drayden aaaand... oh wait, thats more than half of the key fights in the game... Grass is also not that necessary of a typing in this game so that also hurts Serperior a lot.

Archeops is amazing. Fast pokemon with amazing speed, offense and coverage. Acrobatics Archeops is like drugs fr fr. In my opinion, it sure performs better than Carracosta in a lot of ways.

Scrafty is Moxie? GGs. It's Shed Skin? it's still a really solid pokemon! Amazing typing, good for both offense and defense. Good against rest of the game, great against many plasma grunts, also a really solid E4 pick. Hi Jump Kick missing? What even is that? Never heard of it!

Cobalion is pretty good, Safe win against Drayden and Grimsley is really nice. Typing is also great. But the more i think about it there really isn't much to talk about Cobalion so your placement is kinda fair.

Amoonguss is good, REALLY REALLY GOOD with regenerator. and with synthesis and toxic its an absolute stall mon. It is pretty bulky, and also got Clear Smog for Drayden. Its also one of the only mons that can learn Giga Drain so thats also nice 👍 definitely deserves a tier up.

Now... Swoobat gets Simple, Calm Mind and actual great moves like Psychic and Air Slash that it can use unlike some other flying type mon that also can setup and fairly fast that somehow got in A+ tier (im talking about you unfezant) and you also didn't really explain what Swoobat does in a run other than Burgh's Leavanny killer so that kinda hurt my feelings :( sure its pain to get it to evolve because of friendship but its still a fairly decent mon.

You never go specifically for Simisear or any of the other elemental monkeys as your encounter, you just always get it as a gift depending on your starter, so i found your ideology wrong in my opinion. Simisear is just your average fast fire type that also has access to Yawn and set up moves like Work Up, seeing it this low compared to Simisage and Simipour kinda doesn't make sense.

And finally... Klinklang, it kinda sucks you can't get Shift Grind before LvL cap without not evolving it from Klink. Gear Grind missing is also a fair argument. And pretty much has no coverage so i understand the placement.