A lot of strong Pokemon in the 4-12 rankings. While some of these only have one or two consistent sets, those sets have proven to be strong and effective.

Magneton is a powerhouse. Pre-DLC, it was the main contender for Vivillon as an evolution. But with the DLC brings its best evolution: Clefable. Magic Guard Magneton is one of the most powerful wallbreakers in the tier. With a solid Speed stat, and strong moves like Steel Beam and Ice Beam in its kit, there are very few Pokemon that can switch in on this Pokemon safely. Its one fatal flaw is its relatively low Speed and its 4x weakness to Ground. Other sets still make their appearances, such as Levitate from Hydreigon/Vikavolt, or the aforementioned Vivillon, but Clefable is the set everyone knows to watch out for. Magneton is a Special Attacker that you should always be wary of.

Rhydon has returned in DLC2 and shot up in the rankings, which is surprising considering how relatively low it has placed in the VR rankings in the player discussions. Its biggest flaw is its Ground/Rock typing, not being good at all against Water or Grass-types. Luckily, two solid evolutions in Hatterene and Skeledirge (and also the less common, but still useful, Dragonite or Salamence) help it change to a better defensive typing. This has allowed it to use its strength, bulk, and utility to support certain teams quite well. It also commonly ran the Prankster Grimmsnarl set, which is worth mentioning even if I do not have much to say on it.

Vullaby's presence here is interesting. In its initial run before ladder, the common attempt was to run Vullaby with a defensive Pokemon like Persian-Alola, taking advantage of Fur Coat and its solid bulk to be a decent physical wall. Vullaby has taken that to a new level with its new most common set of Vullaby/Gyarados, using Intimidate to keep physical attackers from breaking through it. Other defensive sets like Chansey and Clodsire do exist as well, but Gyarados is unsurprisingly one of its best sets. It does help that its typing + Intimidate gives it a solid matchup into each member of the Big Three.

You all know why Primeape is here. It is here for one simple reason: Hisuian Samurott. Often running Scarf, this Pokemon's access to STAB Sharpness-boosted Sacred Sword and Ceaseless Edge has made it very effective on certain teams. While there are still rarer sets like Dragonite or Skeledirge, no set is as threatening to the meta as this Fighting/Dark monster. While it is relatively frail compared to other strong attackers, it uses the speed from its Scarf sets to get the jump on a lot of its opponents, as many strong Pokemon in the tier are often weak to one of its two STABs.

Girafarig was banned during the Tera era thanks to how strong its Stored Power sets could be. With the Tera ban, the increased number of Dark types in the tier, and the ban of its favorite abuser Espathra, Girafarig has settled into the tier as being a balanced, but still very strong, Pokemon. Often its best set is Toxtricity, taking advantage of Punk Rock Boomburst to do amazing damage to the opponents. However, the biggest change during this ladder was the unbanning of Gholdengo. Girafarig becomes the fastest, and easily one of the strongest, Gholdengo users in the tier, taking advantage of its high Speed and Special attack to make Gholdengo an even more impressive Special Attacker. While that is solid, Gholdengo still has a negative matchup into all three member of the Big Three, so STAB Boomburst sets are normally the way to go (and sometimes even Specs Noivern is the choice for that higher initial Speed).

Dusclops/Garganacl is an amazing defensive titan. Being neutral to Ghost-type moves and immune to status thanks to Purifying Salt, having recovery, utility, and bulk, makes this combo already great. While a couple other combos exist, such as with Corviknight or Incineroar, neither of those other options has seen as much action in the tier.
Edit: after looking at the more detailed usage stats, I have noticed a set I was not expecting: Dusclops/Reuniclus. This set seems to run Magic Guard and Sticky Barb, which seems to be designed to mess with itemless Physical attackers (either Unburden mons or Pokemon you just hit with Knock Off). This is actually really clever and I cannot wait to see what other creative things people come up with.

During the early days of the tier, Misdreavus was commonly used with Masquerain as a Ghost-type Sticky Web setter. However, now Misdreavus has been given much more interesting utility in its evolutions. Competitive or Marvel Scale from Milotic, Fairy type and Aurora Veil from Ninetales-Alola, or insane power from Gholdengo. While some of you may be surprised to see a Ghost type getting turned into Gholdengo's Ghost/Steel type, Misdreavus has one thing in its toolkit which Gholdengo sorely lacks: Will-O-Wisp. Just that one move adds a layer to the Gholdengo toolkit which makes it a very interesting threat to face.

The defensive titan that is Chansey should not come as a surprise to anyone. With an already crazy good HP stat, it can use one of its solid evolutions; Skeledirge, Hatterene, Garganacl, Clefable. Skeledirge and Hatterene are likely the most common, but thanks to its movepool and longevity, Chansey finds itself a niche as a solid defensive Pokemon for these teams. Its usage as a Special wall proves that it has some tricks of its sleeves when given just a bit more power to work with.

Stantler/Ceruledge is a common and effective threat. Thanks to Flash Fire, a number of fights have often come to a standstill of two of these Pokemon facing each other, with neither being able to hit the other. Some do run Weak Armor sets for the surprise factor, but often that immunity is vital for this playstyle. A couple other sets have popped up and are common enough; Stantler/Hariyama for a strong Guts user, Stantler/Maushold for a strong Population Bomb (though that has fallen off more as of late) and Stantler/Lucario for a powerful Swords Dance + Extreme Speed (though this often loses to a lot of great Ghost types such as Ceruledge evos). This Pokemon has been around since Day 1, and has proven why it deserves to stay in the tier.
CE UU notes: tricky choices for this set of bans. Decisions on whether it is the base or the evolution that makes these Pokemon so effective is not an easy answer. My decisions on what to ban from this list are as follows:
Base Pokemon: Magneton, Rhydon, Girafarig, Dusclops, Chansey, Stantler
Evolutions: Gyarados, Samurott-Hisui, Gholdengo, Milotic, Ceruledge
This is likely a very controversial list, but I believe Vullaby and Primeape can co-exist in a balanced CE UU without their most powerful sets.
(Note that these Pokemon and evolutions are ordered by the order they are mentioned in this section)
Edit: usage stats show that more than 80% of Vullaby were either Gyarados or Clodsire, and that almost 90% of Primeapes were Samurott-Hisui
Edit 2: Dusclops/Reuniclus usage shows me just how strong Dusclops is as a base. My initial idea of just banning Garganacl has changed, Dusclops is being banned instead.