It looks like the meta is posting about problematic aspects, so I'll get on this too. Akira and Sevag explained really well already for Slaking and Tera, respectively. I will just be adding some stuff for both. Won't be discussing anything else.
Slaking:
I think Slaking is pretty unanimously agreed as the 2nd best mon in the meta right now, only under Imposter. Its sheer power, lack of viable consistent checks, role compression, surprising longevity all contribute to it being incredibly splashable. The silly thing about current Slaking is that if you compare it to Zacian-C in its prime, Zac-C had multiple extremely good sets, while Slaking is dominating with just one set. That set is as mentioned:

Slaking @ Flame Orb
Ability: Guts
Tera Type: Normal
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Adamant Nature
- Facade
- Tidy Up
- Strength Sap
- V-create / Wicked Blow / [Less good but easily useable coverage moves]
Simple yet effective, Facade sports tremendous raw strength (Guts boosted is the same strength as +1 from old Poison Heal sets) along with an enormous 32 PP, comfortably stalling out Recovery options. While the coverage move choice does show a 4MSS, with V-create being walled by Giratina formes while Wicked Blow being walled by Zamazenta-C, a team still needs to prepare for both less they want to get matchup fished. Tidy Up provides good role compression while Strength Sap provides incredible longevity when Slaking beats basically all sap blockers (Chansey and non-FCs get destroyed).
Now lets talk about the checks. A huge issue with Slaking is that its checks are super specific and are also just not good.
Slaking checks generally don't do much outside of checking Slaking, which is a problem when role compression is so important.
As Akira mentioned, Slaking checks include (all Fur Coat) Giratina formes (lose to Wicked Blow), Zamazenta-C (lose to V-create), and other mons that resist Normal while not being weak to either coverage move (Rock-types and Annihilape). As mentioned before, Giratina's typing is just not good in the meta with weaknesses to basically every other offensive mon's STABs, while Zamazenta-C's typing is almost just as useless without resistances to types like Fairy. Rock-types obviously don't offer any useful resistances outside of kind of checking Rayquaza, while Annihilape obviously doesn't do anything else. Arceus-Ghost's typing isn't bad due to loads of neutralities. Arceus-Steel is the only mon that actually can do something else, except if it wants to check Slaking then it needs Fur Coat so it can't do its superior SpD typing against mons like Flutter Mane and Iron Bundle.
Slaking checks also aren't really good at actually checking Slaking (lol).
As mentioned, a lot of these checks are insufficient by themselves, and also due to the sheer power and potentially PP of Facade, generally require Strength Sap, and due to 4MSS can't really fit a regular recovery move alongside it, leaving them prone to being sap blocked. Considering that the most common sap blocker is base Chansey, a generally decent way of pressuring base Chansey from sap blocking is to use physical moves. However, physical moves are extremely ineffective against Slaking due to its very high Def bulk and Strength Sap. Knock Off, while being effective against Chansey, is ineffective into Slaking. If opting for special moves then said check is highly susceptible to being sap blocked. Mixed attacks is also not effective, Slaking's only weakness Fighting has horrible special moves and also hits nothing, meaning STAB is necessary to force good damage, while Chansey is deceptively bulky on the physical side, making STAB physical moves ideal to pressure that, and obviously running two moves of the same type is more than suboptimal. Dual-type mons also don't work, as Giratina's Ghost-type doesn't hit either, and no other defensive check with dual type has respectable mixed offenses. The ONLY exception to this is Zamazenta-C (and Annihilape)'s Body Press.
Slaking checks are particularly susceptible to Imposter. This is not another one of Chessking's rants on Imposter. It's something that doesn't appear as immediately obvious.
While Imposter is not easy to deal with for most defensive mons, Slaking checks are notably worse against Imposter. This is because some of the best moves at pressuring/crippling Imposter are very ineffective against Slaking. The list includes Knock Off, status infliction from Nuzzle Mortal Spin Toxic etc, Spikes and Stone Axe, and even Spirit Shackle (unrelated but free Anchor Shot pls thx). This makes it very difficult to fit moves on Slaking checks that both allow it to actually function as a reasonable Slaking check while also not inviting Imposter in for free. Checks like Giratina, Zamazenta-C, and the more niche checks are also rather bulky when transformed by Imposter and difficult to force out, especially with Ghosts' immunity to trapping and Zamazenta-C's immunity to Poison. Giratina-O has a better matchup into Imposter by threatening with decent damage SE STAB moves, but it should be noted that Griseous Core boosted Modest Draco Meteor doesn't even deal half to Imposter. Ghostceus is the only one that actually has a great matchup against Imposter, but Ghostceus is far from a reliable Slaking check due to its susceptibility to Wicked Blow and sap blocking.
To top it all off,
Slaking has an incredibly high number of opportunities to switch in and wreck havoc. As mentioned before, Slaking easily switches into common utility moves ran by defensive mons, while its high Def bulk and Sap makes it capable of switching into physical moves too. Its SpD bulk, while not great, does let it switch into some weaker moves like unboosted Arceus-formes and unboosted Flutter Mane. No other offensive mon since Poison Heal has this easy of a time getting in and being as resilient against punishment.
We can actually compare Slaking to the recently banned Miraidon and OriPulse. Slaking is more centralizing in defensive countermeasures, as Miraidon checks generally can multitask by checking other SpA or providing utility, while OriPulse needs Fire-resist but those mons are still effective at being a physical wall against non OriPulse physical wallbreakers and resisting V-create is always solid. Slaking has more opportunities to switch in, as those wallbreakers have to generally be slow pivoted in to avoid Knock Off and Status, and are also susceptible to hazards. Slaking also has just as effective wallbreaking power.
In terms of why Slaking didn't get more attention in the survey, I personally underestimated it when I completed the survey (I ranked it a 7, but I also didn't rank it higher because my 10 was Tera). I think in general people haven't fully adapted to the Guts set either, as I have seen a lot of Pop Bomb sets still. BTW MG sets are still ok but it should be noted that
252+ Atk Guts Slaking Facade (140 BP) vs. 252 HP / 252 Def Arceus-Dark: 306-361 (68.9 - 81.3%) -- guaranteed 2HKO
252+ Atk Life Orb Slaking Population Bomb (10 hits) vs. 252 HP / 252 Def Arceus-Dark: 390-470 (87.8 - 105.8%) -- approx. 6.3% chance to OHKO
252+ Atk Slaking Population Bomb (10 hits) vs. 252 HP / 252 Def Arceus-Dark: 300-360 (67.5 - 81%) -- approx. 2HKO (Wide Lens)
And MGLO despite being stronger needs to be boosted for reliability and cannot really boost speed.
Tera:
Oh boy. I think I covered Tera in a prior post and the points haven't really changed. Sevag also basically covered all the absurd damage Tera boosted wallbreakers can do.
What is a noteworthy change from superpowered wallbreakers in prior generations and this generation is the
nerf of Recovery.
8 PP Recovery is such as massive deal against wallbreakers, because it means that at best there's an equal pp of Recovery to the main move the wallbreaker is spamming, and more commonly it means there is less Recovery. This allows these extra hard hitting wallbreakers to just repeatedly spam the move until all PP is gone. Sevag provided the example with Specs MRay being able to just sit there and click Boomburst repeatedly into a supposed check. This in particular is a notable difference between this meta and the NDBH meta. OriPulse is more handleable in that meta because its much easier to stall out V-create PP by using Heal Order. Basically high powered wallbreakers are more of an issue in this meta, something being able to consistently deal 40+ to checks is much more dangerous now, and with Tera many wallbreakers are able to accomplish that.
Defensive Terastallization also still causes a very unhealthy amounts of 50/50. This can be on both defensive and offensive Pokemon. Sevag provided examples for offensive mons already so I'll provide a defensive mon example.
Replay. This replay also happens to show the potency of Slaking.
Turn 19 Akira hard brings in Slaking on FC Waterceus, this is a pretty safe play since I revealed Toxic already and STAB Revelation Dance was not going to deal enough, while I had to keep Waterceus healthy and preserve Recovers for Koraidon.
Turn 21 Slaking deals over half to my supposed Slaking check, FC Giratina-O. Granted I am not +Def, but not even +Def Giratina-A can reliably avoid the 2HKO here.
Turn 22 and 28 are the key Tera turns here, consider the possible scenarios that could've occurred for both turns.
1. Slaking switches out, Giratina-O doesn't Tera, favourable for latter since Slaking is forced out. This is what happened Turn 22.
2. Slaking switches out, Giratina-O Teras, largely favourable for former since now Giratina-O cannot check Slaking anymore.
3. Slaking stays in, Giratina-O doesn't Tera, Slaking KOs Giratina-O.
4. Slaking stays in, Giratina-O Teras, Giratina-O KOs Slaking. This is what happened Turn 28.
In other words, this matchup that would've been completely favourable and winning for the Slaking now becomes roughly a 50/50 thats in slight favour of the Slaking. Without Tera, Akira would've comfortably won, but instead loses his 6-0 matchup mon due to getting 2 50/50s wrong.
Also please don't interpret this as "Tera is necessary without Tera Chessking would've just lost to the Slaking thus Tera good it lets team check mons". Slaking is a broken mon and so Tera being necessary to check it is just broken checking broken. Using "Tera helps check all the wallbreakers" is also false since wallbreakers are stronger in the first place due to Tera, and monotypes are not good defensively anyways. Plus we have been completely capable of checking wallbreakers through good teambuilding without requiring Tera in previous generations so its not like its not possible.
Later in that replay my Slaking was able to make a lot of progress by doing stuff like switching into Zacian and heavily pressuring Akira's team despite having a FC Annihilape, only not immediately winning due to threat of reverse-sweep from poisoned Imposter (hence the turn 81 switch out).
Conclusion: Tera should be banned, Slaking is banworthy regardless of Tera (arguably better without Tera?), GF give us something nice like a Marshadow or Dhelmise or something. See you guys in OMPL.