Thanks for tagging me, and I think this is a great idea! Here's what I was thinking for my viability rankings for tldr:
I've largely finished filling in the descriptions, but here's another tl;dr -- pretty much everything in S-A+ warp the tier, but Rachi and TTar more so than the rest. Think Meta belongs this high up w its general utility and one of the main reason rachi has somewhat lost its iron grip on the tier alongside lefties tran. Skarm fall down to A, but still great, clef a little further back bc offense slant of the meta, think gyara and dnite need some exploration but define HO, Empo is fantastic rn imo, as is suicune for its ability to softcheck HO and generally be annoying to almost any team style on the right team. Rose spikes on the rise (rose, gengar, cune, flygon), paraspam (zapdos, starmie, machamp, blissey) a little further down, HO (azelf, gyara, dnite, sometimes uxie, empo, meta) on the rise, stall a little on the downswing, zone balance (zone, clef, gliscor, slowbro, breloom) a little on the downswing. I think qwilfish and kingdra are the only swift swimmers worth using in pure rain (although def on the rise) (ludi might be worth it not on dedicated rain). Celebi and scizor are due for a rise w offensive np and sd, respectively. In the future, maybe we'll see the meta in more of a defensive dominated state like predug ban, but rn, offenses and balances feel pretty good to play.
S Rank:

Although it doesn't have as iron grip over the tier as maybe it did pre-dug ban, I (and i think many others) still think rachi is best mon in dpp. Defensive WishTect rachi is still chokes out a lot of offenses, all of its cm sets are still threatening, as are its mixed sets and anything in between. It has a huge effect on the tier, almost forcing lefties on otherwise offensive mons like heatran, zone, or pert so they can withstand repeated ih while letting very slow builds like paraspam run no scarf bc it can kinda handle dd'ers w body slam + iron head. I think the meta has well adapted to it, so maybe the other s mon will overtake it in future iterations, but today, I think rachi belongs as the top S. Some sets I think deserve some more usage (if they havent already) include toxic + iron head, hp ground mix rachi, cm + iron head, and cm wish rachi. Idk how i feel about band, but it did like 70 w fpunch to zone when i tried it, so maybe?

I think tar is the only other mon that can fit in S, as although many mons "define" dpp, Rachi's blanket checking, Iron head, and versatility as well as Tar's (special) bulk, Pursuit, and Sand (among other things for both) give it its identity. Tar really can fit on almost every archetype, dd sets can fit on HO, super bulky set w lefties or a scarf can fit on stall, utility sets can fit on bulky offenses, and pursuit/band can fit on offensive paraspam, among others. It provides an instant check to Lati and Tran (if it avoids the burn) among others, and spinblocks starmie pretty well, letting you fit more options on your spikes stack. I think theres still a lot to explore w tar, from the coverage options, speed, and item on utility sets, the stone edge slot on scarf, the non stealth rock/pursuit slots on super bulky tar, and the coverage on ddtar. I think subpunch and band (outside of just w otr zong) should prob get some more love.
A Rank:

Heatran is interesting to rank. It is the best Rachi (and most steels in general) counter in the tier even if rachi can tech for it w HP ground, it is one of the best lures in the tier for water/special walls/burning ttar with magma + Boom (and sometimes Taunt/will o). Defensive sets can be quite restrictive in the builder w repeated Lava Plume burns and its huge bulk. It can be a terror to offense w or w/o tspikes w SubTect or SubMetal Sound, and it is one of the best sr users in the tier (can lure in star that way too) as well as can be one of the few rotom absorbers will-o besides clef. However, I don't prescribe to putting it in S, cause for all of its advantages and love of no longer having to worry about Dug, it can't do all of those rolls at once -- if you run rocks, you feel you're missing a critical coverage option, and you're almost forced to run lefties to stay alive long term against jirachi unless you have other rachi options, defensive sets often wish they had five slots. I have a love/hate relationship w scarf, cause using it as speed control means you better have a good option for dd'ers unless you plan to boom on them/lose to ddtar. Tran really is on the borderline (after reading some of the arguments below me), and I think there's definitely an argument for S. I think some sets that should get some more usage are LO (it really is a great lead), Taunt, SubBoom, and Modest Will-o sets as well as the bulky set plume set.

Latias, despite its dislike for the three mons above it, feels right here. Its either the three best general scarfers in the tier with rotom and flygon w its ability to only need two attacks + access to healing wish + trick, its the best spore absorber (don't get pursuited!) w specs, its defensive sets can feel impenetrable, and can even sweep w cm sets (although I don't think they are viable as they were w Dug). Its resistance profile is great for providing some more help against offensive waters/loom/tran/zapdos. Speed is definitely getting dropped on this thing, on pretty much every set but scarf, and I think it'll continue to be one the key pillars on pretty much every style but HO. Some sets I think should be used more are Roar on the defensive set, a little bit more speed on modest specs, and maybe CM + Twave

I think Meta definitely deserves a rise up the viability rankings, as both lefties and trick iron (as well as like agility and scarf) are imo really good rn. It is such a great blanket check to pretty much everything in the tier; its so bulky that max hp doesn't really die from full to anything except heatran and like banded flygon/swampert, and even w/o any bulk (ala the agility set), a resistance berry is all it needs to tank a DD hit for example and explode. It is one of the best leads in the game, it gets up rocks really well, the lefties (and trick iron set if you're willing to blow the trick on it) really help offense stay alive against opposing wishtect jirachi and clefable, it lures Rotom/skarm/zap really well to take advantage with something like ddtar or CMCune. I feel it won't rise much more than this, but I really like meta here, it just provides a ton of utility and can fit on pretty much anything. An underrated set (besides the ones I've mentioned) is band, although I think the first four sets will do you just fine
(my writing was getting pretty lazy here previously, this section and beyond is rewritten as of May 6th)

I think loom belongs this high up bc of how restricting it feels in the builder -- Spore + immunity to status + healing in sand + strong fighting stab makes it one of the best noob killers in the tier. I think loom is one of those dpp staples that is largely immune to the weathers of the tier bc spore is so good and it is still one of the better ways to break stall combined w other breakers, as well as be generally really annoying for offenses w its bulky set. It certainly likes Dug being gone. I think it belongs in a+ despite not being as splashable as the others simple bc of how debilitating loom can be to poorly built teams. Some sets that I could see being used more include w/o spore like sd + protect, protect in general, and the good ole bulky sub punch set

Rotom is this high up for me bc although it isnt quite as splashable as the mons before, it, like loom, has one of the more debilitating tools in the tier w its bulk, resistances, and access to will-o-wisp. Like Tran, rotom is one of the main threats I feel teams need to account for wrt to burn, as resttalk rotom can sit on a lot of offenses forever and just burn them. It is also key on a lot of spike stack teams bc it is immune to spin, but its not quite as essential as it used to be in that regard. It is prob the best general scarfer in the tier (hot take I know) as w trick and its coverage/speed, can revenge/cripple just about everything. SubSplit (or even charge beam) sets are not quite as good as they used to be, but are still quite good. Just watch out for ttar! I think sub sets should be used more, as well as general utility weather clearing sets too (w rock or even colbur)
A Tier:

Like Excal before me, I also believe Skarm should be brought down into A tier. I think metagame forces over the last year have shoved it down a peg, as it doesn't have as iron of a grip over the spikes role w Rose's prominence, nor does it enjoy the zone builds that took advantage of no Dug/were gaining prominence even before that. However, it does like how many offenses can flat out lose to it ability as a wall -- I like to not use double hazards on it for this reason. Skarm I think belongs here, but is due for a bit of resurgence as both a heavy offense hazard stacker (it is probably the best in the game at getting both sr and spikes up quickly) and as a wall, esp w rose spikes pushing mag balance down a peg. I think Taunt should get some more love, as well as maybe even endure salac berry.

Compared to my peers, I have somewhat less of an opinion to Clef, although it certainly is still fantastic even w/o Dug enabling it. Clef is still the best general special wall in the tier, as bliss can only really used on spin teams or very specific offenses and the other options pale in comparison. Clef's toolset is fantastic in general, w Encore (pls use it more), healing wish, a usable special attack stat (it doesn't have to just be cm), alongside the classic sr and knock. Clef has warped the tier, similar to mons above it, but I feel the adaptations on how passive it can be at times have really hurt it (such as w Loom, HO in general, rose/skarm spiking on it, Gengar, etc), so much so that I've knocked it down here. I could definitely see it being A+, and it was in previous iterations of the metagame. Some sets I think could be used more are special attacking sets w/o cm, healing wish, and trying to fit it on more balanced builds than hard stall.

Gengar is definitely one of the winners of this iteration of the meta w rose spikes prominence and people exploring the options beyond sball and blast. A Gengar w its glasses on (ie hitting blast and will-o) is one of the scariest threats to face, as it only gets stopped easily by the relatively predictable scarf tar. LO sets really punish offense w speed and power while still being threatening to stall, bulky sets are good at crippling everything and nailing stall, and I still feel gar has a lot to explore w explosion, destiny bond, all kinds of cool coverage and utility. Like in ADV, there is always a gar set that can mess you up. I think sleep talk is def a cool option, as is trick black sludge, destiny bond, and even classic ones like counter or subsplit. just don't use hp fire, pls

Pert is one of my more used mons, and for good reason, bc it feels so versatile. It can be really fat or be pretty fast, hit from special or physical or both, be a great sr user, be a pretty good status absorber w refresh, and generally be a pain in the butt for offense teams to deal w. Something I've been doing is running some decent defensive investment on my offensive perts, like 108 def w max hp to help tank like ddtar better. I think Pert might be due for a rise, as it is great on pretty much any style but HO and can be stylized in many different ways. However, I don't have quite as high of an opinion of it as my peers -- I think this is more up to how good the above mons are than pert is bad. Lets loom in a little too easily at times, weak to (toxic) spikes and can feel walled somewhat easily depending on the set, but I love it for how dependable it can be on all different kinds of offense. I think Protect and curse pert deserve a bit more love as well as refresh sets being great against defensive tran and rotom.

I think the meta is just starting to explore how versatile gyara can be. No longer relegated to either just an endgame sweeper (or older dpp players might remember as just a fat wall), gyara has been explored as a lure w both wacan and cb and one of the best ways to abuse swampert. It is one of the pillars of HO in this gen, as well as I think the old resttalk set is pretty good in this meta (Fighters are largely useless against it, forre is good alongside it, Intimidate is great). CB and early dd sets are one of the better enablers of SD empo due to weakening water resists, and using it early in this fashion before rocks get up helps mitigate its weakness to SR. I think there also is some exploring out there for it beyond the item slot, with coverage beyond just waterfall eq and ice fang (someone showed a LO double edge set that could be cool). I think the meta has adapted a bit to it, but so has gyara w like wacan and lum but be on the lookout for gyara's rise.

I think Dnite and Gyara belong together as destructive sweepers that can blow holes for each other. Gyara is more versatile and has more defensive use, which is why it gets the nod from me, but Dnite I think is still quite underexplored compared to gyara. Dnite has the more immediate power w outrage (koing pert at +1 sometimes is glorious) and has that immediate priority. Defensive DD and defensive sets in general are quite underrated even if they need a ton of support. Dnite is also a pillar of HO (not as much as gyara but still) bc of how almost any team can lose to it and how it breaks open walls for others. CB can 2HKO anything in the tier and has really strong priority to boot. I have problems sometimes on how easily it can die at times to sand + SR + potentially LO and how slow it can be even boosted. It also isnt quite as good as a breaker bc of that nasty ice weakness.

People who watch my games know I use a lot of suicune. I feel suicune, despite on how specialized the builds can be w it, is quite effective at checking just about any team w the right set. It can soft check dd mons w offensive sets, its bold crocune sets are fantastic win cons, and sub sets are great in both rain and on rose spikes. It really needs to be support well, but w Water spam, stall, rose spikes, and rain, cune can feel unbeatable in some match ups. HO really struggles w it, balance can get run over by it, even stall can fall apart against cune quite easily. It really likes a grounded poison type, as well as a way to help bust through water resists and skarm/rachi, but with these (like in rose spikes) it can be great. I think Roar should be used a bit more, as it can just 6-0 if you get in a cm war, but cune really is fantastic.

I think Flygon is on the up swing right now. It is one of the best scarfers in the game, its LO set can really bust open stall (although I also agree it isn't quite the world beater everyone thought after spl), and the CB set is still really good. Gon has always been a good scarfer (its one of the best tools against HO), but I think people are making good builds to showcase its utility among many sets (rose spikes, w trick iron or zone a la august balance, LO + spikes). It also loves being largely immune to hazards and has roost to boot, so it can abuse those rest talk rotoms and bulky Trans from earlier. I think the defensive set might be rising, although still want to see some tourney success w it. It is a great way to bust through bulky teams w hazards down

I also find Gliscor quite similar to Flygon. Both are ground types w recovery largely immune to hazards that can bust through stall (gliscor w taunt/knock/being annoying and flygon w LO mix or band). Gliscor also has a great defensive niche due to how bulky it is and the toolkit it has. It doesn't shut down stall quite like it used back in the day, but SD sets and general bulky sets are still really good. Gliscor also is somewhat of a loser in this meta, as stall is a bit down and it can't quite get through its checks (lati, waters, Gengar) like Gon can. However, it is still a great way to shore yourself up against Fighters and general physical threats. I still think it belongs up here w much it can shut down some teams w taunt and its bulk profile. I think the specially defensive set is due for some love, as well as branching out on the SD set w items/coverage.

Empoleon is fantastic right now, almost so much I want to put it higher in A. I think people are finally branching out from just the agility and lead sets and exploring its fantastic typing and movepool. I always feel empo puts in a lot of work when I use it, whether as a balls to wall offense on either physical or special side, a tank sr setter a la the august set, or a fully specially defensive set. Even specs can be quite effective against stall teams. It's one of the better lati absorbers in the meta, as well as has a unique niche against water spam and rain. Knock, coverage, roar, sr, it has a lot of options to be useful in a game to game basis. Agility (w or w/o petaya) and the lead are still great too. I think it can fit on pretty much any team and is quite due for a rise in the metagame.
A- Tier: (might flesh these out w more time, but the order is set in this snapshot of the meta imo)

Talk about rose spikes doing well and some new found versatility w scarf and offensive spikes, but still frail. epitome of an A- threat. due for a rise

Fallen a bit in the meta due to being a bit useless against defense, really liking spin (hard), and only really fitting on specific para teams/stall for the defensive set. However, off sets are monstrous against HO, defensive sets (w spin support) shut down some offenses like little else, and scarf and agility still feel quite good. Still looking for the next great zap builds

Zone's utility is great, I think people were overblown in discarding balances w it in favor of rose balance. I've been experimenting a lot w zone offense too, and its working quite well as skarm has had a bit of resurgence in the meta.

One of the classic anti-offense tools, I find zong a little bit harder to use nowadays, but is still quite good w zone support. Think OTR is bit bad in this meta, but trick sets are good and still like tank zong and defensive zong for its ability to set up rocks well and wall what you need to. It is a pillar for rain too.

The classic HO enabler, think Azelf is due for a rise in the meta. Think people have started to think more versatile against it, but for me, I can only go so high on a mon that has essentially one good niche that is does very well.

The other good enabler, Uxie belongs right up here w azelf. It is slightly worse at the HO enabling, but is better in midgame utility as very bulky anti-offense and getting rocks/knock/status

Still as scary as ever, a full HP machamp is one of the more frustrating things to face in dpp. I think previous iterations of the meta were better for it, but shoutout to being one of the better ways to deal w DDTar in the meta. Paraspam is a little underrated right now, while behind screens it can be quite menacing.

Inconsistent, but still quite good on like rain (specs kingdra is the best rain abuser in the tier). Think the DD sets are ok, but its the main rain mon for a reason.

I had starmie a lot lower originally, bc of how much i despise using the bulky spin set or the colbur/LO sets but the specs set really is what the doctor ordered for this thing. Four attacks (or three attacks w trick is best on thing, but trick + spin aint bad either. Wrt to its bulky spin sets, they just feel really meh to me, especially as people have started just using their sr weak mons earlier where as ones w more midgame utility like zapdos have fallen a bit. Still really essential for those paraspams/defensive teams, I just hope we see more specs running through offense

Another very inconsistent threat, luke I think is due for the same early game wallbreaker treatment that dnite and gyara can be used more. It doesn't have quite their versatility, but I think w like endsalac and other innovations like the resistance berries, luke can maybe return to its prominence on some HO teams.
B+ Tier:

I think Blissey is due for a rise, as it really has incredible utility in the right match ups and has a huge movepool. Be on the lookout for rises in the future w different teams than paraspam and the occasional blissey offense and hard stalls.

Nido is another pillar of stall and is one of the better sources of tspikes in the game. Think previous iterations of the meta were better for it, but again works great on many versions of stall

The tree I think is quite underrated, as SD has really revitalized its offensive sets even as the old leech versions are a little bad due to clef and generally being slow and weak. Hail hits almost everything, and sd can work on both offense and very defensive teams if you build around it. Shame it has so many weakenesses

I think Scizor is due for a bit of a rise as well. While the mighty have indeed fallen, Scizor's offensive SD sets feel better than ever, w zone often being slow, rachi commonly not running fire punch and the general speed of the meta making bulkier answers less common. Still looking for a great HO build w it!

I think celebi is due for a bit of rise. Even w the crippling weakness to tspikes, uturn, and its proclivity to be set up on, Celebi has quite a unique defensive profile. NP sets are good in my opinion (maybe a bit of a hot take)

Hippo, destroyer of offenses everywhere and providing sand. Still think it has a bit of versatility left in the tank, but it is truly great at getting (and w the dropoff of starmie and spin and general, keeping) rocks and sand up.

This B+ tier is really where I put all the oh how the mighty have fallen mons? I do think ape is rather bad right now, as it really misses power, and if it gets that power, it dies super quickly. It has almost no defensive niche and only really can get in on doubles. I do think those random ladder teams mess me up when i don't account for it, but ape is in dire need of some innovation, as it really struggles in the current meta.

I think hera is super underrated. It is p great imo on paraspam as a general faster cb threat, esp as gliscor usage is trending downwards and it doesn't have to worry about dug anymore. Megahorn and CC hit so freaking hard, and it has some cool versatility on its cb slots, not to mention how destructively powerful its sd sets can be. Be on the lookout for this thing!

As one of the few great water resists in the tier, Milo can be back breaking to water spam, HO, and rain in general at times. Again, I think previous iterations of the meta might be better for it, but Milo still puts in work game to game on balance teams and on hard stall.

Ahhh forre. I think forre is also due for a much needed resurgence as a semi reliable rapid spinner against non resttalk rotom teams. I think its usage fell off a cliff a few years ago, as it required a ton of reads just to get enough free turns to do what it was supposed to on stall. However, w the rise of protect on it, I think it is ready for a comeback on hard stall. I've run boom, eq, even counter in that last slot. Just focus on what makes it good (spinning and spikes) and don't try to overload it too much (primary dragon resist and stopping offense) and you'll be just fine w it.
B Tier: (beyond this point, I think the ratings are a little movable -- the above are pretty locked in imo)

Qwil is pretty mandatory on rain nowadays I feel like bc of its general utility over other rain sweepers. I am also curious to see if it may have some utility outside of rain w tspikes, boom, taunt, twave, and others.

I feel kiss liked previous iterations of the meta better, but it still can put it work as a trick scarfer or as a general nuisance w subroost nasty plot on paraspam.

Mamo always feels on the cusp of viability, but it just falls short bc its attacks outside of eq are so weak and it just a tad bit too slow w its weaknesses and vulnerability to hazards. Knock off sets can put it work though.

Mesprit is actually awesome, I wish I could put it higher. It has a lot of utility, it is really fat. I think it could work pretty well over the midgame azelf people below are describing.

Man I remember when donphan was memed as a horrible spinner in dpp, but excal has shown it can put in work w the right support w odor sleuth and rest.

The older version of the meta were deffffinitely better for slowbro, as it hates rose spikes w a passion, but minus that mu, it can feel unkillable at times. Being the best machamp counter in the game as well as good stop gap to dd mons is also fantastic.
B- Tier:

Tenta can actually be quite effective in this meta, as knock has really revitalized it and it doesn't have to worry about Dug. Still think it is way too vulnerable to common threats, but I think we still are waiting for the great build w this thing.

Camel! Camel actually has quite the role to play on HO. I think its builds are being explored more even though it is quite niche. I used to discount it until I used it in action and it can work pretty well on the right squad.

Think Knock off sets could be cool, sleep + more bulk than rade is cool. Think it def should be explored more.

It's great, but I've only really seen it on that Excal team that everyone and their mother spammed on the ladder/non-mains in team tours. I wish it didn't need so much support bc its toolkit is really great.

It hits unbelievably hard, but it only really fits on a specific style of paraspam. Hard to make work elsewhere

Staraptor is 100% underrated and should be explored more. There is little better than clicking banded adamant brave bird from the lead and like 2hkoing TTar w a good roll. Shame it is a little useless against stalls that have phys def rachi and/or rest talk rotom.
C+ Tier:

Specs vap is a fantastic lead, it really can set off water spam really well if Pump accuracy cooperates. Shame it lost bp, and wish sets are unviable imo.

Quag needs a team built around it, but it really can invalidate a lot of offenses w its v unique toolkit

I think Raikou is due for a bit of a resurgence, as it really can put in work w its movepool, power, and speed. However, it really needs a grounded poison type partner (rose) and can still struggle w defensive teams.

I think the days of classic ludi rain are a bit over, but I think it can find a new roll as a one-off rain sweeper or as a general utility mon.

Cress really took a hit with its main enabler in Dug being banned, but it still has quite a niche. Its a fantastic dual screener w lunar dance, it is so insanely bulky, it also has some pretty good CM sets if you're willing to support them w Zone/TTar removal.

How the mighty have fallen. I think Shaymin is a bit underrated, as seed flare can really stack up some damage and it has great stats. However, it doesn't really enjoy meta trends and really wishes it had more moveslots some times/hates t spikes w a passion.
C Tier:

Specs mega is a cool lead, it is also one the best loom sleep absorbers until loom started running protect. It still is a tad unviable w that insane sr weakness, but I've seen it put in work. imagine if it was dragon/flying!

Weavile is one of those mons that sometimes I forget about in the builder and crits and freezes me when I face it on ladder. It's alright I guess, but it is so incredibly vulnerable to everything while having attacks that don't hit hard enough.

Coco loves this thing. I really havent gotten it to work well, but I see the potential. Maybe one day

Dual Ghost spikes teams are cool. Makes it a little hard to cover everything, but this mon is cool, definitely could see it more in this meta as an alt spiker.

I personally think gastro is pretty bad even before dug ban. Even w a perfect set-up team and against the right opponent, it always felt vulnerable to luck and smart play against stall, and it got manhandled by a lot of offense. Interested to see how it adapts/how it doesn't in this meta.

Similar to Ludi, I think the days of Kabutops rain are over. It just doesn't give enough utility to rain. However, it is still pretty decent at sweeping.

I guess I need to experiment more w the TrickScarf set, but it seems pretty good. Definitely niche, but has all the right utility.

I often forget about crobat in the builder, but it can be quite effective as a stallbreaker.
Everything else