
A+ to S-
I am the only person who voted to move Hisuian Samurott into the S ranks, however I truly think this Pokemon deserves it.
Ceaseless Edge is a genuinely insane click; I cannot state enough how absurdly useful it is to be able to layer Spikes while dishing out damage, especially considering Sharpness bolsters it into reliable STAB territory. Ceaseless Edge off of its offensive profile makes every other Spikes user in the tier feel so awful to use in comparison when you could be simultaneously exerting pressure, which is the biggest drawback of Spikes otherwise. Everyone knows this, but let me take this opportunity to explain the metagame-based nuances around it and how this actually propels it into the S-ranks for me.
This dynamic of offensive damage output in tandem with Spike stacking lets Hisuian Samurott structures more reliably get them up, since Ceaseless Edge being Hisuian Samurott's best Dark-type STAB lets it force switches easily. This not only lets it support itself with its own Spikes in the long run, thanks to its priority options, but this also lets it stack even more chip on Dark-type resistant switch-ins with the move itself. However, the big reason why this dynamic is so metagame defining imo comes in its ability to use its Water-type STAB to threaten the tier's most splashable removal option, how stringent hazard removal is in this format, how easy it is to pair Gholdengo with Hisuian Samurott, and how Great Tusk's Close Combat is a luxury as opposed to a fixture. Because Hisuian Samurott sets are becoming less shy to run bulk investment, it's a lot easier for it to contend with standard Great Tusk as well. This makes it stupid hard to clear hazards without either losing a defensive centerpiece to its Water-type STAB or having a gameplan
just to clear its Spikes. It's super easy to enable these Spikes with the fact that Hisuian Samurott can also hit hard with a nasty Knock Off or you can easily run Pokemon like Gliscor to strip away Heavy-Duty Boots in the long term.
While this alone 100% warrants A+, I think it is propelled by Hisuian Samurott's underrated versatility giving it way more applications than its stats would let on. It is a staple in Hyper Offense and Bulky Offense alike, and a lot of this can be attributed to the dynamic it possesses with its Spike stacking and the tier's removal, alongside how many sets it can run to anchor its team. AV is probably its best set hugely because of the optimizations made to its bulk investment; the CTC spread or something similar lets it take on a lot of punishment, which can be a big help to more nuanced offensive gameplans and can be slapped onto 90% of teams tbh. Focus Sash is a fantastic lead and is complemented well by it being able to compress the team support you'd get from less all-out offensive teams thanks to its access to Taunt and Knock Off. Swords Dance throttles balance and also works great on Focus Sash sets. HDB 3a sets also work great thanks to its access to Taunt and Encore to both reinforce its team and create more openings to spam Ceaseless Edge. Choice Band and Choice Scarf are both really solid, especially since it has Flip Turn to midground into more reinforced teams. All of its sets are rounded off well with access to strong priority, letting it also secure some nice KOs if it can't quite pick off its target; Aqua Jet into the Donphans is particularly great since it often can't OHKO with Razor Shell/Aqua Cutter. I find that across all of its sets, it is just so stupid easy to put on teams. In fact I feel as though a majority of the teams I build end up having this Pokemon just because of how versatile it is as a hazard setter and teammate.
This Pokemon to me is, alongside Gholdengo, the incarnation of the really volatile hazard dynamic this tier has. Because of that and how well it can lean into it with its wide applications, I truly believe it deserves to be in the S ranks. Not S outright, but S- is perfect for it imo given that its stats are really its primary weakness and can be a major Achilles heel at times.

A- to A+
I continue to be astonished at how underrated this Pokemon is. Not only is its defensive profile just insanely useful in 90% of matchups, but it spreads status like little else in the tier across Discharge, Thunder Wave, and Static while also being a potent defensive/offensive pivot with Volt Switch or U-turn depending on your team's needs. Its set permutations are shockingly (no pun intended) varied.
It can rock a lot of investment in one direction or another, which makes it a great defensive glue that can provide near guaranteed progress or let it be a potent threat. Offensive sets are mad powerful; I've been running a Fairy Tera Blast set with Hurricane and Volt Switch which messes up its primary switch-in in Raging Bolt, and Volt Switch is a great way to funnel in Gholdengo and Slowking-Galar, which also lets it deal generally solid chip to Gholdengo and overall enable powerful offensive teammates.
I think Zapdos does a lot of what makes Moltres potent, but with far more applications thanks to not being 4x weak to Stealth Rock and having less exploitable weak points in general.

B to A
Pecharunt is just kind of crazy. I feel like it took a really long time for people to catch onto it (myself included) because most people were trying to make use of Nasty Plot. While this set can definitely work from time to time, the reality is that a Kingambit-centered metagame makes it a matchup fish, ultimately. However, recently Parting Shot sets have come to play, and this is where Pecharunt becomes a truly excellent Pokemon.
Its solid resistances, perfect Speed tier, and goofy base Defense let it act as a fast disruptor that can also handle a lot of punishment, making it a great alternative to Gholdengo that is more resilient into Iron Valiant. Parting Shot is pretty crazy with it, since it can use this defensive profile to weave in and out of the game thanks to how much of a perfect blend these qualities end up being. Weakening switch-ins with this move can also be a big deal for offensive setup teammates or helping defensive teammates bounce back/handle offense more reliably. Its natural Physical bulk is really felt even with just max HP. Great Tusk can't even come close to OHKOing it, and Booster Attack is a roll in the Pecharunt user's favor, which is crazy and also a highly useful quality given that it would likely be serving the role of your spinblocker. Tera Water lets it expand its defensive applications into matchups where its bulk is most coveted, which makes it really useful in a bevy of matchups.
Malignant Chain with Poison Puppeteer is insanely annoying and can shut down setup sweepers in a pretty noteworthy way; even if Confusion doesn't pan out, badly poisoning your target is really compromising in its own right. The risk of this move is low since it's a very potent STAB move in its own right, but the reward is high with a peak that can shift momentum completely in your way if the odds are in your favor.
Overall, a really useful Pokemon; Parting Shot really lets its powerful disruptive qualities shine in a serious way and I think it's rather unsurprising that it's been seeing an uptick in usage lately.