Yeah but other than that, why would I want to use Swampert over one of the several other Water/Ground-type Pokémon out there such as Gastrodon for example, who has Countercoat, three superior abilities and the almighty Pain Split for starters? Literally a better Physical Movepool and Bide are the only things it has over Gastrodon, which pretty much leaves it kinda outclassed. When Mega Swampert comes there will be even less reason to use regular Swampert as Swampert will only be good for the fact that it has a Mega Evolution. C- is okay for it but the problem with Swampert is competition,
especially for a spot in a Ground-type Gym team where it is horribly outclassed.
Nidoqueen: B Rank (Or either B- or C+)
Nidoqueen for all intents and purposes is a Female Nidoking except the fact that it is slower and has less Attack, pretty much making it nearly outclassed by Nidoking. The thing it does have over Nidoking is the fact that it is a Female, which is relevant due to the way Rivalry works. It beats virtually the same threats Nidoking does and can be an effective teammate for Nidoking if you wanted to be crazy and try a double Nido onslaught core or something. Her ranking pretty much depends on how much she is considered to be outclassed by Nidoking but the fact that she plays similar to king means that Nidoqueen is not to be underestimated.
Simipour: C- / D Rank
Simipour is a niche Water-type who simply takes on the role of a fast, offensive Water-type. With a Water Stone in tow, Simipour can become deceptively powerful and Simipour has an okay support movepool to boot. While this separates the water monkey from its fellow Water-types, the competition is still omnipresent and the fact that skill frog made waves at the start of this generation did Simipour no favours. It is by no means a bad Pokémon but Simipour's problem is that it is somewhat outclassed, especially in the fast offensive Water-type build because of skill frog. C Rank is okay for it though.
Hitmontop: D Rank
Contrary to what Geodude said, this is not a Doubles+ ranking list (Well OP implies Singles by mentioning 1v1 matchups) and in Singles, Hitmontop is pretty bad and faces a lot of competition from the other Hitmons. Even as a spinner he gets competition. The only thing he has to separate himself from other fighters in the Singles environment is his eclectic set of abilities and a massive Sp. Defence boost from Rare Candy that nobody really cares about. It is basically outclassed in a singles environment and D Rank is fine.
Gourgeist-S: C- / D Rank
This is basically a case of "why would I want to use this over Necturna?" Firstly, it is crazy fast. 114 Speed assuming a +Speed nature is nothing to scoff at and with a Size Class of 1, it can reliably dodge quite a lot (this also differentiates Gourgeist-S from its larger forms). It also comes with three useful abilities (Pickup / Frisk / Insomnia) which are generally better than Forewarn and Telepathy in a Singles environment. Finally with Trick-or-Treat, Gourgeist-S can reliably hit the majority of opponents Super Effectively by using its signature move before spamming powerful Ghost STAB like Phantom Force and uhhh Shadow Sneak or Shadow Ball. This pretty much helps make up for its lack of offensive presence. It also has a similar support movepool with a 100% Accurate Will-o-Wisp, Pain Split and in Gourgeist-S's case, annoying moves like Destiny Bond, Trick-or-Treat and even Worry Seed and Light Screen. It is much better in Doubles than Singles but in a Singles environment, Gourgeist-S—while generally outclassed by Necturna—definitely has a niche that can make it worth using.
Swoobat: B- / C+ Rank
The classic Stat boost abuser and probably the best of the bunch when it comes to standalone users. For those unfamiliar, the goal of Swoobat is to abuse Simple to jack its Sp. Attack and Sp. Defence to maximum values as soon as possible before making up for lost actions really quickly via a spammable (generally) 26 BAP nuke that can 3HKO many neutral targets and even 2HKO some SE targets. The introduction of Weakness Policy this generation made Swoobat a lot more dynamic and as a floodgate, puts the opponent into a bit of a bad way. Either they hit it with a Super Effective move and let Swoobat get access to a 26 BAP move after just one action, or they left it hanging to its Weakness Policy and let Swoobat set up without losing too much health. Swoobat also has a lot of tricks to assist it in getting that setup more smoothly as well but yeah. As a stat booster, the usual anti-stat boost tech will typically work against Swoobat alongside other problems like frailty and the fact that it is nothing without the stat boosts. B- or C+ overall is a fair assessment.
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That is all for now I guess. #anotheriartldr