Thread doesn't seem very active atm so I'll make some nominations.
Seismitoad should rise to C+. I'm pretty sure Seismitoad was already C+ before the viability rankings changed, and I honestly see no reason as to why it dropped. The most comparable thing to Seismitoad is Gastrodon, which is currently B rank. While the two of them are very similar, Seismitoad's niche as a rock setter is really useful. As a stealth rocker, Seismitoad has a relatively easy time getting rocks up thanks to it's two immunities, allowing it to switch in on something like Volcanion or Mega Manectric and forcing them out. Its matchup against hazard removers is pretty solid, being able to force out Tentacruel and Excadrill with Earthquake, threatening Starmie and Lati's if they switch in with Knock Off, and being able to knock off Skarmory's leftovers as well as a potential burn with Scald, which can really hurt Skarmory. Having a rock resist on the team is appreciated as well, and prevents things like Terrakion from just killing everything on your team and allows you to play around it. The abundance of grass types in the meta is obviously a downside for Seismitoad, but in the turn they switch in, you can still set up rocks and try to fish for a burn, which really dampers things like Mega Venusaur. Other ground types, such as Garchomp and Landorus-T, can't really do anything back to Seismitoad, whereas Seismitoad can usually force out Landorus-T do to Scald and proceed to set up rocks and can screw Garchomp over with toxic do to its lack of recovery. A major weakness of Seismitoad is its lack of reliable recovery and being vulnerable to toxic and will-o-wisp, so Wish and Heal Bell support are appreciated. Overall, Seismitoad is decently strong in the current meta and deserves a rise.
Staraptor should rise to C. Staraptor has two solid sets in Band and Scarf, with each just erasing a specific play style. Banded Staraptor just murders bulky balanced and stall teams, with few things that are able to reliably check this thing. Defensive Landorus-T is 2HKO'd most of the time, while all other sets are outright OHKO'd after stealth rocks. Hippowdon has seen a decrease in usage, which makes Staraptor's life that much easier (Staraptor can 2HKO, but really doesn't like all the recoil). Teams that rely on a pokemon with a flying type resist such as Rotom-W and Tyranitar get easily demolished do to the coverage of Close Combat and STAB Double Edge. One of the few things that CAN reliably check Staraptor is Rhyperior, which receives very little usage do to the abundance of grass and water types, and overall being outclassed by other pokemon as a stealth rocker. Against stall teams, the opponent will need to rely on Skarmory to keep Staraptor at bay. With access to Final Gambit, however, Staraptor can just take out Skarmory with a bit of prior damage (preferably in the mid game), in which you can then proceed to break past the core. The other set, Scarfed Staraptor, excels on taking on offense (though it still has a great matchup against balanced teams). If the opponent relies on a single flying type resist such as Terrakion or Thundurus, Staraptor will usually be able to apply enough pressure on an opponent to get a KO. Strong priority such as Weavile's Ice Shard or Bisharp's Sucker Punch threaten Staraptor, but they'll usually have a hard trouble coming in. Sand is still pretty common, and Scarfed Staraptor can easily pose a threat to the opponent's team. While Staraptor can't outspeed Excadrill in the sand, Staraptor's access in Close Combat allows you to threaten Tyranitar, in which they'll probably lead with in order to get sand up. The biggest problem with Staraptor is that it gets worn down easily do to recoil and weakness to stealth rocks. However, the recoil doesn't hinder Staraptor enough to stop it from still being able to put a dent in the opponent's team, and hazard removal is an unwritten law in the current meta. To sum it all up, Staraptor's a pretty cool pokemon in the meta, being able to put in work against the playstyle your team is weak to. For all these reasons, it should rise.
Conkeldurr should drop to D. Conkeldurr's niche in the current metagame is to act as a Dark and Rock type check. It's only good set, Sheer Force, is decent, being able to hit hard. Having access to Mach Punch is great, allowing it to be able to threaten offense teams. With all this said, Conkeldurr just isn't that good in the metagame. The Sheer Force set's main goal is to come into something, take a hit, predict the switch, and hit that pokemon with a supereffective move. E.g. Conkeldurr comes into a Tyranitar, tanks a Stone Edge, and predicts Skarmory will switch in and proceed to use Thunder Punch. With this in account, Conkeldurr is extremely easy to play around. There's also the fact that it gets worn down fast do to having to tank hit after hit, along with the fact that Drain Punch doesn't heal for much and Life Orb recoil is still there. Getting worn down wouldn't be that much of a problem if it wasn't so slow, having to rely on predictions to come in and then relying predictions again to actually deal some damage. Compared with other fighting types such Mega Medicham who just press one button, Conkeldurr is really lackluster. It's priority, Mach Punch, is just so weak, failing to OHKO things like Terrakion and Mega Lopunny. If you predict the switch and go for something else, but your opponent predicts your prediction, then you have a dead Conkeldurr. Scald is still common, and since the only relevant set is Sheer Force and not Guts, burn renders Conkeldurr useless. There's very little reason to use another fighting type on your team, such as Terrakion, and therefor Conkeldurr should drop to D.