Nidoking Suspect

Personally I don't understand why people say the Nidos can't be tiered separately because there really isn't a reason they can't be, they're two individual pokemon that play differently, have opposing stat distributions, fill different roles and even don't have the exact same learn set - notably Queen can get Crunch and Pursuit where as King gets Head Smash and Megahorn, obviously not a major deal, although it all adds up and she clearly Queen has the better end of that deal. Slowbro and Slowking are in the same boat as the Nidos are yet no one cares about those two being in separate tiers.

Imo Nidoqueen actually has the better end of every deal between them. For example King's stats are supposed to focus on speed and power but realistically those stats are lacklustre anyway. The only reason he hits hard at all is down to sheer force and the coverage he has but Queen also has both of those things so her missing the 10 points in both offences really doesn't matter that much and neither does her lower speed stat as Nidoking's isn't that high anyway only being 85, if he really wants to take advantage of the speed he needs to use a scarf but considering his coverage is maybe the biggest factor into him being good, locking him into 1 move isn't what you want to do, this really limits the amount of uses he has. Nidoqueen on the other hand has a huge amount of uses, including the same ones that Nidoking fills.

Queen's power is often overlooked and disregarded but in reality she can output an extremely similar effect when invested correctly. Imma include one of many replays from ChrisKarp that shows the powerful side of Queen that people can forget: https://replay.pokemonshowdown.com/gen7anythinggoes-616740045
Nidoqueen performed pretty well that season (S6), picking up kills at a standard surprisingly close to or better than King's with Chris going 15-6 with it and actually picking up more kills than the Kyurem-B on his team. This is the most kills either Nido has ever gotten in 1 season of the IPL. Burn also grabbed 8 kills too which is impressive considering his record was 2-8 -22 that season (soz burn), while Nidoking wasn't picked at all in either division.

The added bulk she has allows her to run phys def, sp def or just generally bulky sets. It means she can set rocks/tspikes and actually still be useful the rest of the game. She can also perform as a bulky attacker, an all out attacker or a scarfer if needed. The possibilities of sets she can run to a high tier 2 standard are endless, Nidoking just can't because his stats simply don't allow him to. Nidoking can be a LO attacker or a scarfer and that's about it, for both of these roles there are too many Pokemon that just do it so much better than him that he can't be considered a tier 2. Considering all of the above Nidoqueen is far more versatile than King which makes her desirable for more coaches and for more draft styles. Nidoqueen can fit on any roster or any team any week because of it’s capability to run so many different sets effectively. It's exactly this that lets her compete with the rest of tier 2 unlike King and this is that warrants there being a one tier gap between them.

Putting his counter part aside he also just can't compete with the superior wallbreakers (not to mention setup mons) such as Mence, Staraptor, Hydreigon, Diggersby etc and the recent addition of Lando-I who with it's speed, offensive ground typing and mixed capabilities has stolen King's thunder. There are so many Pokemon in that tier that are either absolutely devastating or pretty damn versatile but Nidoking just isn't one of them. He would be better suited in tier 3 with the other less valuable nukes like Haxorus, Darm, Emboar, Dragalge as that's all he really is; he would definitely be a better tier 3 but much more fairly priced for the minimal value he brings to a team.