I know that Rhyperior was mentioned quite recently and I have a "bit" of input there. I'd like to nominate it for something like Rhyperior for B. It, in my opinion, is one of the best blanket checks and anti-meta pokemon available. The first set I'd like to discuss is an anti-meta Custap.
Rhyperior @ Custap Berry
Ability: Solid Rock
EVs: 252 HP/80 Atk/132 Def/44 SpD
Brave Nature
- Earthquake
- Rock Wrecker
- Counter
- Stealth Rock/Fire Punch/Megahorn/Rock Blast
This set, while odd, checks and counters an incredible amount of common pokemon. It, in a 1v1 situation, beats Kangaskhan (non-Low Kick), Aegislash, Azumarill, Garchomp, Charizard X, Talonflame, Ferrothorn, Landorus-T, Gyarados (non-mega), Mega Mawile, Terrakion, Thundurus-I, Zapdos, Blaziken and a variety of lower-ranked pokemon. After finishing off many of these pokemon, it will find itself in Custap range, allowing it to get one last hit.
Rhyperior @ Rindo Berry
Ability: Solid Rock
EVs: 252 HP / 108 Atk / 80 Def / 68 SpD
Brave Nature
- Metal Burst
- Earthquake
- Rock Blast
- Avalanche
This Metal Burst Rindo set, while also an odd set, is also a great counter to many common pokemon. It beats the following S and A ranked pokemon: Kangaskhan (non-Low Kick), Aegislash, Azumarill (usually), Garchomp, both Megazards, Talonflame, Ferrothorn, Landorus-T and I, Gyarados (non-mega), both forms of Gengar, Mawile, Thundurus, Zapdos, Breloom (sometimes) and many lower tiered pokemon. Because of this, it's a great anti-meta pokemon.
Rhyperior @ Choice Band
Ability: Solid Rock
EVs: 164 HP/252 Atk/92 Spe
Adamant Nature
- Megahorn/Avalanche/Poison Jab
- Earthquake
- Stone Edge
- Hammer Arm
This Choice Banded set makes for a great wall breaker and, again, an anti-meta pokemon. It can beat Kangaskhan, Aegislash, Azumarill (Poison Jab), Garchomp (Avalanche), Charizard X, Gengar, Talonflame, Cresselia (Megahorn), Ferrothorn, Landorus-T, Mawile, Terrakion, Thundurus, Zapdos, Blaziken and lots of lower-tiered pokemon.