Rises:
Carracosta
B+ to A+
Carracosta proved itself to be the best SpDef wall in the meta during PMPL.
Armaldo
B to S
Anyone who played in PMPL knows why this mon is going to S, it's basically the Landorus-Therian of the meta with its splashability, set variety, and high utility.
Bastiodon
B to S
Another clear standout from PMPL, Bastiodon 1v1s pretty much the entire meta and can wall entire teams in the right situations. Its lack of recovery can hold it back but Rest variants also popped up during the tournament to cover that weakness.
Gourgeist-Ancient-Large
B to A-
Grassy Terrain teams were very strong in PMPL, and Gourgeist-Large is their enabler.
Alticombat
B- to S
Token brokemon of the meta. SD sets on this thing are ridiculous, and Band sets aren't far behind.
Aerodactyl
B- to A-
Aerodactyl has been historically great, though it had fallen off a bit in the recent meta due to how team were built around beating it. Those cores showed up a lot less in PMPL though, and new innovations like Band and DBond have brought Aero back into the limelight.
Brawlutra
B- to B
To quote a tour player, "I use Brawlutra when I want Armaldo with Spikes over Rocks."
Omastar
C+ to B+
Omastar has shown itself to be a staple of very bulky teams, with Regenerator plus massive bulk and a large utility movepool making it a must-slot in order to check key offensive threats.
Cardantis
C+ to B
While it hadn't been seen much since its nerf, Cardantis received new (un)life during PMPL, with players experimenting with Misty Surge sets (both offensive and defensive) to some success.
Pesbasil
C+ to B-
Button clicker with Band or Scarf. Very one-note mon, but its STABs are hard to switch into, so it does its job well enough.
Lapras-Abyss
C to C+
Was used a lot during the tour due to its defensive profile + Rough Skin, though it's still pretty passive and loses to a lot of common offensive mons.
Conkeldurr-Conch
D to C+
Pure Power sets actually saw a fair amount of use during the tour, as its good natural bulk and few weaknesses make it a pretty functional tank.
Sigilyph-Ancient
D to C+
Tinted Lens makes this fairly hard to switch into, and buffed Petroglyph lets it clean up games in the right hands. Psychic/Ground is also shockingly good offensively in this meta, which all comes together to make a Sigilyph a pretty good mon, though it does require some skill to use effectively.
Heliolisk-Ancient
D to C
Not as bad as the D tiers, though it's not great either. Galvanize Double-Edge is very strong, and Quick Attack is great for revenge-killing Alticombat, which gives it just enough utility to be usable.
Salazzle-Ancient
D to C
Saw some use in the tour for its powerful, hard-to-switch-into Specs Ice Beams.
Drops:
Skeledirge-Ancient
S to A-
The power dropoff after this mon got a SpAtk nerf has been very noticeable, and without the ability to run away with games it's mostly just been used for its (still quite good) defensive profile.
Icaruff
A+ to A
A somewhat surprising drop considering how much Calm Mind sets popped off in PMPL, but I think it's moreso that people think the mons ranked higher are better overall, rather than Icaruff being any worse.
Yizolt
A+ to A
Similar to Icaruff, Yizolt was a very strong and often-used mon in PMPL, but people just think the top 4 + Carracosta are better.
Venopleura
A+ to B+
Venopleura's inability to actually beat SD Alticombat has removed one of its main niches in the current meta, making it harder to justify on teams. This is exacerbated by how common Ground coverage is on physical attackers, limiting the number of mons Venopleura can actually check defensively.
Crobat-Ancient
A to B+
I think this is mostly a case of tour players not using Crobat enough, as the mon is still plenty good, and arguably especially so in the current meta, as it feeds on teams that rely on Bastiodon and Carracosta as their SpDef walls.
Gourgeist-Ancient-Small
A to B+
The main concern regarding this mon was splashability, and while I think the competition with Gourgeist-Large is a very real knock against it, I don't think Gourgeist-Small is all that hard to slot otherwise, as its drawbackless unwallable STABs + Ground coverage are obscenely strong when played well, so this could just be another oversight from the tour players.
Swishivish
A to B
Swishivish, on the other hand, has had a real falloff. While its STABs are great on paper, in-game it's difficult to bring in and the payoff is often too low to justify Swishivish's SR weakness and crappy speed tier.
Eleffigy
A- to B+
Mostly just the meta settling. Eleffigy is still good, it was just ranked a little too high on the previous VR. Archeops usage is also trending down in recent weeks.
Ungabunguss
A- to B+
Same deal for Ungabunguss. Still good, just ranked a little too high previously. Also doesn't help that it can't actually beat some Tyrantrum sets.
Tauros-Ancestor
A- to B-
Another mon that was barely used during PMPL, which could be biasing this ranking a bit, but Tauros is generally considered to be very hard to slot and not worth the effort to enable, though I personally think it has a lot of unexplored potential even after its nerf.
Carriguana
A- to B-
Tour players generally trended away from using Carriguana, as its fairly defensive nature left it too slow for many teams. It's still a solid option, and B- is probably underrating it a bit, so we'll see if it can reclaim a higher placement in the future.
Cradily
B+ to C
Post-nerf, Cradily is just really passive and hard to justify on teams. This is especially true in a meta where Kabutops and Alticombat are the two best offensive mons.
Moscourge
B+ to C
Moscourge went almost completely unused in PMPL, with its extreme frailty and weak STABs making it hard to justify on teams.
Goldoco
B to B-
Goldoco can often feel just a bit understatted for what it wants to do, especially in the SpDef department.
Swampert-Ancient
B to C+
Swampert was repeatedly unable to provide value to teams in PMPL, and while I was able to get much more value out of it in testing, I can understand a drop from the showing that's publicly available.
Dracomizer
B- to C
Very awkward to run and hard to justify over other options for hazard setters. Also can't do anything to stop Kabutops from spinning away all the hazards it sets.
Hemlophosaur
B- to C
Another awkward mon. Can get good value with its great defensive typing and Poison spreading, but generally struggles with many defensive cores and common mons like Carracosta and Omastar.
Servachne
C+ to C
Bastiodon is S-tier and on like half of all teams - very hard to get value with Webs in a meta like that.
Gourgeist-Ancient
C to D
Impossible to justify over its other forms.
Meganium-Sonic
C to D
Impossible to justify when it literally can't do anything to Carracosta/Skeledirge and can't switch into any offensive mons.