Yep, i agree with the idea of switching Amoonguss to B+ and Tangrowth to A-. Tangrowth isn't only dedicated to fill a lot of teambuilding holes (Ground- and Water-resists). You can make it flexible to cover a specific threat of your team, as HP Ice to cover more reliably SD Grounds, HP Fire to avoid set-up scenarios vs M-Zor, or even some tweaks like Toxic or Rock Slide, or putting a Rocky Helmet to punish Mega Lopunny and Bisharp more reliably. I see Amoonguss doing a more unidimensional function, and although i don't care about the "after it sleeps someone it's passive" argument too much, Amoonguss fills a couple of nichs overall (covering Fairies and Water-types), he's more easier to exploit depending of his coverage, being a lot spikes | set-up bait, and his neutrality against Ground-types is a relevant thing as well.
I think Ferrothorn should drop to A instead of A+, not because of Volcanion nor Spikes competition, but simply because the metagame is unfriendly to it. Stuff like HP Fire Cube, HP Fire Lati or Diancie (if Diancie uses EP that means that it's usually paired with a Zone) and a couple of common trends makes him kinda unreliable or forces it to scout and open more space for your opponent to outplay you, and there are some annoying teambuilding flaws as well imo. There are a lot of builds that i want to slap Ferrothorn because because it gives valious resists (Steel utility mon + Rocks or Spikes + water-resist), and the niche of alleviating the Rain Offense matchups. But in the other side of coin, if you choose him instead of dudes like Heatran and Klefki, that only compounds the weakness of the team against the Flying-types (think about Torn-T), if you don't use Iron Head + Thunder Wave, that means that Clefable can outstall the Gyro Ball PPs and use him as a set-up bait anyways, if you use Gyro Ball + TWave, you forgo SR or Spikes or Leech Seed, so it tends to get overloaded on his moveslots or functions (for example, fantastic Azuma switch-in, but hates switch-in vs Rotom-W and Manaphy, something which doesn't happens with Tang or Amoonguss that often), so people need to be careful with Ferrothorn's pros & cons. Don't get me wrong, i still think Ferrothorn is a pretty solid mon, but i honestly don't think that he's A+ material, but i guess people overrate him a bit because he's /splashable/ on lazy FGW or common Sands cores, but w/e.
Bisharp should drop to A+ to A too, although it's the one of main reasons (with Weavile) that encourages people to slap Keldeo or a Scarftar to not get swept after it setups a SD, but again, the metagame isn't too kind for it. People are overprepared for it and use Keldeo and Garchomp with a insane frequency, and even if you give him proper support (overloading him with Sucker Punch + priority of other things like M-Zor or Azuma), there are conventional ways to circumvent that, like pairing Keldeo with a Healing Wish user, or making their Rotom hit a higher speed benchmark. If you have a Hippowdon, Gliscor, Keldeo or Scarftar on Bulky | Balanced squads Bisharp won't be doing too much anyways, same thing applies for (Semi-) Stall. But at least his niche as a Defiant is pretty important for a lot of offensive teams, and makes people play carefully with Lando-T, and being a good emmergency button with priority and Clefable is obviously very important.
Slowking and Nidoking deserve to be B+. The former is pretty convenient, you can make his spread flexible and it'll be consistently switching in against LO Torn-T and Medicham simultanealy, and having a good time in a CM War is Clefable is wonderful too, unfortunately it's more easier to be punished by Pursuit users, unlike Slowbro. Nidoking is probably the best offensive Clefable switch-in (maybe after Excadrill) and puts pressure on a lot of builds, but that is it. It won't provide any extra niche (unless if you want to innovate with Toxic Spikes or VERY SOFT Electric switch-in, i guess?), and it's frail as hell. It sounds more useful than stuff like Crawdaunt and regular Scizor for me, though.
Also, A- is perfect for Hippo, he it isn't that outclassed by Lando-T or Chomper (unlike Lando-T he doesn't force you to play more carefully against Bisharp, and unlike both he can switch reliably on Mega Manectric and Raikou, Thundurus is a bit tricky tho, also don't forget his reliable recovery). It's more specific for Balance or Bulky builds and less splashable than Lando-T | Chomper, but that doesn't mean that he's bad on his job. Sorry if i kael'd here too much :(
