Dark:
Zarude’s a good offensive Pokemon on Dark teams. However, its ability to cteam Water teams very well is what earns it as a B ranked Pokemon considering having an otherwise borderline impossible matchup against one of the best types in the metagame is undesirable.
Bisharp is still good but it is worse than Tyranitar.

Morpeko doesn’t have any niche anyone on Dark because Zarude gives the type a much more reliable Water cteam.
Electric:
Heliolisk is a nice tech option on Electric that can run Grass Knot to beat Water, is immune to both Mimikyu and Azumarill’s priority against Fairy, and being decent offensively with notable coverage to take advantage of.
Fairy:

Fairy teams have been dropping Grimmsnarl more and more to fit Pokemon such as Galarian Weezing and Primarina.
Galarian Weezing and Primarina have taken a surge of viability and are both good options for Fairy’s last slot alongside the previously mentioned Grimmsnarl. Galarian Weezing has nice utility with Neutralizing Gas as well as being a Toxic Spikes setter and absorbent. Primarina’s setup can prove to be deadly when paired with Klefki’s screens support.
Gardevoir and Ribombee have both fallen out of fashion. Sticky Web Fairy just isn’t great considering Fairy already has Klefki’s screens as support to go off of while Gardevoir is rather one dimensional and very niche if you would like to tech for weather.
Fighting:
Toxicroak has surged with usage on Fighting because of its ability to deal with Fairy along with a Water immunity and Toxic Spikes removal. On the other hand, Lucario has fallen out of fashion compared to other setup sweepers that are easier to fit in teams.
Fire:
It’s better off with what’s ranked at C.
Ghost:
It’s harder to use as a Stealth Rock setter than Galarian Corsola which fits better on teams due to its ability to blanket check threats that would otherwise rip though Ghost.
Grass:
Rillaboom is one of the best Pokemon on Grass at the moment. While it is not as good as Ferrothorn, it is considerably better than what is ranked A.
More Grass teams are being centered around balance, so Venusaur and Shiftry drop a rank.
Assault Vest Amoonguss is a great way to check special attackers as well as absorbing Toxic Spikes on balanced Grass teams.
Zarude’s a cool Choice Scarf user, makes sense to rank it on the same rank as Virizion, another Choice Scarf user with slightly different attributes. While Virizion does get STAB Close Combat and Toxic, Zarude’s U-turn prevents it from being a momentum drain against foes it cannot best by itself.
Ice:
Kyurem is better than the B ranked Pokemon, so it’s now A ranked!
Normal:
Heavy Duty Boots mean Blissey is better than Chansey at filling the role of a Teleport pivot and wall; explaining Blissey taking Chansey’s tank and Chansey dropping as a result.
Porygon2 has become a more niche pick on Normal and many teams drop it to make room and tech for more matchups.
Porygon-Z is extremely niche as a special attacker so it drops another rank.
Poison:
Drapion is a good pick as a Psychic immunity if you aren’t preparing for Electric; its Toxic Spikes and Knock Off are great attributes for breaking down defensive types.
With the rise of Fairy, Choice Scarf Toxtricity is a good option as a revenge killer that can also beat Togekiss behind a Substitute which would threaten Poison teams entirely otherwise.
Psychic:
Other Pokemon have gained popularity while Gardevoir has been falling out of favor.
Toxic Spikes absorbent + setup is good enough of a niche to put it alongside the likes of Pokemon like female Indeedee, Reuniclus, and Starmie.
Steel:
More Steel teams have been dropping Bisharp lately in favor to fit other, more consistent Pokemon such as Excadrill, Jirachi, and Cobalion.
Cobalion is the best Choice Scarf user on Steel and comparable to Jirachi and Excadrill viability wise as offensive Pokemon.
It’s better than Scizor as a Fire neutrality that’s valued. It is still hard to fit though, which is why it isn’t going any higher than C.
Water:
Keldeo, despite not nearly as good as Toxapex, is better than Gastrodon, Slowking, and Primarina, so putting it at S reflects on the viability gap and how dominant balance is at the same time.
Rain teams have been falling out of fashion for more all around consistent balance builds. Pelipper dropping to B, as well as other rain- reliant Pokemon such as Seismitoad and Kingdra reflects on that.
Slowking, Primarina, and Gastrodon are staples on balance teams that have been surging in viability. Slowking and Gastrodon are both great defensively, while Primarina serves as an excellent wincon in many matchups across the board.