I will make my nominations in descending order of rank:
B+ to A-
This is not new, Kingler is a terrifying sight in many team previews, because it usually means you are going to lose one pokemon when it switches in. There are almost no counters to it except Gougeist-Super, Gastrodon, and Pyukumuku. What makes it A- rank imo is its speed stat which is quite high, even with an adamant nature. It allows Kingler to easily outspeed standard Mesprit, Hitmonchan, Eelektross, and Aurorus and basically Ohko the latter three while dealing huge damage to our fav rocker. Also, it is able to sweep slightly -not even heavily-, slightly weakened teams via agility+liquidation nuke. Counterplay includes gurdurr as a check, scarf pyroar and healthy sprit in offense teams, plus aftermath/machpunches. I know a decently prepared team won't let it set up/ will revengekill it, but Kingler can function very well as a breaker and just not click agility. It will always get the kills you want it to get and wallbreak vs balance with SD/just spam if no gastrodon so I think it should be ranked higher than lycanrock and musharna and reach the level of floatzel and drampa.
B to B+
Silvally-F, while not being an awesome pokemon, is a largely reliable pivot, defogger, counter to every fighting pokemon that isnt gunk shot primeape, while boasting a correct/good speed tier. It has enough bulk to last throughout most battles, provides a solid stab, flamethrower for the ever-so-common ferroseed and parting shot support. But what makes it good in the metagame is its access to defog, which paired with all the former traits turns it into a great role compressor for offense teams. Defog is very important here, because how rare are the viable defogger users in PU since altaria is gone. Also, it's arguably one of the best offensive support pokemons imo alongside with skuntank and mesprit, and always does its job well in the current meta. So to conclude, the invaluable combo of defog+fighting-resist typing makes it a legitimate candidate for B+.
B to B-
Throh is quite underwhelming right now and it's pretty hard to justify it over gurdurr or hitmonchan: it actually is a mix of both, with solid mixed defenses and good attack. However it will rarely be successful whatever set it is running, due to a low speed stat and a slot-wasting, unreliable recovery method in the form of resttalk. I think it's best set would be choice band, because how easy it is to stop the circle throw set (and how much support it requires), but again gurdurr is by far a better choice because of eviolite-boosted stats and access to drain punch, in tandem with machpunch to make up for the lowspeed. I can hardly find a good reason to use throh, even typenull can work similarly but is bulkier.
E to C-
I have been thinking and working for a while on this pokemon, so I will be honest in my post, basing it on my experience because nobody actually uses it to its full potential (and I probably didn't either). Whether I like it or not, I have enough arguments to justify its niche in PU, besides it's quite easy to understand them. Shiinotic is probably the best counter to gurdurr and calmmind spiritomb (any spiritomb actually). It also walls Kingler to death which is huge. In addition, it is extremely effective vs trick room teams due to its abysmal speed (check my RMT/think 2 secs and give it 0ivs speed+relaxed) and rain to some extent (spores a rainsetter and cripples the incoming sweepers); access to spore make it a not deadweight pick because it will seriously cripple one of the opposing pokemons, and can then proceed to leech seed/ strength sap. It fits decently in some Bulky Offenses / Balances as a glue for gurdurr, trickroom, lanturn (becareful with icebeam) and notably as a hard counter to gastrodon thanks to gigadrain (choose between giga and leech tho, 4MSS: leech/gigadrain/hidden power fire). Strength sap means you can quickly get all your health back. It also makes a good role compression for partners like Aggron and Type:null, which are slow and will let their counters switchin too many times, notably gurdurr which can't be handled in the long run with stuff like mesprit (trapped) or clefairy/spiritomb psychic. I'm aware of the magmortar issue (vital spirit is problematic), but waiting for its ban makes 50% sense because pyroar and aurorus will still threaten shiinotic. I just want to highlight the humble tools shiinotics can provide to your team and make this post now because I will have forgotten to do it after mag is banned or not.
>RMT (includes proofs of peak/tournament wins): https://www.smogon.com/forums/threa...off-roomtours-peaked2-ladder-w-2loss.3632126/
>One replay where shiinotic shines: https://replay.pokemonshowdown.com/gen7pu-729120760 (would have almost swept a
magmortar team if hitmonchan didn't crit freeze lategame)
Why C- ? I definitely think it is as good as noctowl and servine and more useful than toucannon or vigoroth, that's why I'm suggesting C-. Togetic, Prinplup and Cacturne (D rank) are far from providing a similiar
viable role compression : shiinotic can't do many things but does them very well, contrary to these ones.
Why use it over tangela? It's a good knock off absorber contrary to tangela, realiably beats gurdurr, takes on spiritomb, and underspeeds all the Trick room sweepers (with
the spread). It is also less "passive" thanks to effect spore which quickly activates after a few contacts and can cripple additional mons.
EDIT: I've got other Shiinotic teams, if it may help you deciding whether it is possible to build with it in practice and what mons would benefit from it ask me!