Nidoking is, as far as wallbreakers/balance breakers go, pretty mediocre. Its slow, its frail, its typing gives it weaknesses to four common offensive types (the Ground-, Ice-, Water- and Psychic-types) and it isn't even overly powerful. Sure, its coverage is insane without it even needing Hidden Power. I respect that, and it is part of why it is even ranked in the first place. However, this thing is shredded more by offense than most other wallbreakers and balance breakers are. This is due to the aforementioned problems (barring the power one), and really its coverage only brings it so far, resulting in it only an optimal choice for a wallbreaker on, like, one or two in every fifty-or-so teams. However, that is why it is in D. I don't personally feel that it should move up, as there has been literally no change in the metagame that favors Nidoking - if anything, the recent metagame shift from balanced to offensive makes the metagame even
more hostile to Nidoking as it gets completely shredded by said playstyle. As a balance breaker (imo what it can be most accurately called), it is mostly outclassed by multiple Pokémon in various ranks (which I will list under the headings of "high rank", "mid rank" and "low rank" for the sake of comparing it right through the rankings):
- High Rank: Mega Gardevoir, Manaphy, MegaGross, Hoopa-U, Azumarill, Mega Metagross, Mega Medicham and Gengar
- Mid Rank: BandTini, Band Tyrantrum, SF Conkeldurr, Specs Sylveon, Hoopa-C, Mega Swampert, LO Hydreigon, Bandnite, Crawdaunt and Diggersby
and bludz
- Low Rank: Megastoise, Staraptor, Entei and Pangoro.
Honestly, that is a long list, and it is a big part of why it is in D as opposed to C- (the same level as Pangoro), as really it is pretty outclassed on, like, 48 of every 50 teams. I have probably even missed a few, as I honestly can't be bothered to go over the rankings again, and I have covered both the special and physical sides of the spectrum to account for the (shitty) physical sets which are awful at balance breaking anyway. This is a big problem for Nidoking, as a balance breaker with great coverage is great until you consider how rarely it will be optimal. It can't come in on anything other than resisted hits and faints (and passive pokemon, but stall is mostly dead now). It is outpaced by a large chunk of the metagame and struggles to take a hit from anything that is moderately powerful and has a way to hit it for at least neutral damage. However, I'm not saying it should be
unranked - just that it shouldn't move up.
Nidoqueen, however, I am mostly neutral on - although I have been leaning towards C- since it was ranked (but really its placement is inconcequential to me). Most people in this thread probably know this, but I'll say it for the sake of clarity. Nidoqueen and Nidoking play different roles, and I don't really like when people compare the two as they are not comparable from a competitive standpoint. Sure, they share typing, abilities, name themes, evolutionary lines and most of their movesets, but their stat spreads mean they function differently in battle. Nidoqueen, as AM so aptly stated, is a tank. Specifically, it is a tank which acts as an offensive hazards user. Its access to both Stealth Rock
and Toxic Spikes (which Nidoking also has access to) gives it a good niche over other hazard-laying tanks such as Heatran, Tyranitar and Dragalge. Additionally, while it lacks reliable recovery, its bulk is good enough for it to take a hit or two, even enabling it to take certain weak SE hits - such as a non-STAB Ice Beam/Icy Wind or an uninvested Scald. This means that, assuming it doesn't get critted, it will always get at least one hazard up. The best part about Toxic Spikes is that you can lay a different number of layers depending on the archetype of your opposing team (for example, you are better off with one layer v.s. hyper offense). However, you all know how T-Spikes work - so I won't go into it anymore. The key reason that I feel that it has the possibility (not need) to move up is because this flexibility allows it to fit onto a wider range of teams than the current D ranks. Its customisable two/three-type coverage in combination with the ability to carry either one or two types of hazards - depending on the team's needs - allows it to fill a niche that not much else can really fit. Sure, you have the odd SR+Spikes tank out there that can perform something similar, but the pressure provided by Toxic Spikes>Spikes sets it apart as it allows for increased flexibility in your tactics tactics depending on the opponent and its potential to open up moveslots on teammates that may have carried Toxic otherwise to break fatmons like Slowbro - not to mention it providing guaranteed pressure on non-Magic Guard CM users (e.g. to heal up/rest and providing permanent poison for (grounded) Natural Cure users like Celebi/the blobs and Magic Bounce users (namely M-Sab). Anyway, I'm not that adamant about whether Nidoqueen should go up or stay down, but I am adamant about Nidoking staying down.
tl;dr:
Nidoking D-->D
Nidoqueen D-->C-/D