Sorry Corumba, I also have felt quite annoyed at unaware walls myself so I understand your frustration, and since it wasn't my main focus in the post there, my response about clef was not as thorough as it ought to have been.
The point of bringing up garchomp and rilla was not to point out that they would beat clef in the 1-v-1, but to show that in practice, unaware clef is often more of a check than a true counter. What I mean here is that it's actually somewhat risky to swap unaware clef into a strong set up sweeper directly. Obviously if they boost on the switch, clef is safe, but if you switch in on a life orb-boosted attack directly, it's gonna sting, especially if there are rocks/spikes up. Beyond this, your point about softboiled stalling is valid, as an unaware clef user I have done it many a time myself lol, but when you do this continuously over and over, the chance of a crit often becomes non-negligible, and if not a crit, often other rarer move sideffects, things like stat drops (which do affect unaware pokemon) and rare burn/para/freeze chances start to build. I mean clef runs heal bell a lot, but you only get 8 of them. if you keep your set up sweepers in the wings, it is feasible, if time consuming, to force an opponent to run out of heal bells with a consistent status spreader, many of whom can switch into clef. When I have played against strong HO players with unaware clef, I have seen many examples where even if they don't have an outright counter, they will essentially sac a strong wallbreaker like garchomp to get clef down to ~50%, and then they can manage to apply enough offensive pressure make it quite difficult for it to get a free switch in to heal, since it lacks regen and is punished by hazards. And that is to say nothing of steel set-up sweepers like scizor, bisharp, and the rarer SD iron head aegislash that outright beat it.
One thing I will sympathize with, and offer a solution to, is your complaint about bulky Clef/Slowtwin/Blissey/Metal Bird/Toxapex teams. Are these a pain? Absolutely. Let me share
some non-choice mons that I have used or have seen others use on the high ladder to break through stall teams, including unaware clef.
My disclaimer for all of these mons is that I do not think that I am giving you the overall best set to use, and a couple of these mons themselves are on the fringes of general viability, but if you have 5 mons on a team that synergize well, and you really need to murder stall, you can try these out in your last slot.
Victini @ Heavy-Duty Boots/Expert Belt
Ability: Victory Star
EVs: 252 Atk / 16 SpD / 240 Spe
Adamant Nature
- V-create
- Bolt Strike
- Glaciate/Toxic/Energy Ball/Grass Knot
- Power-Up Punch
This one is pretty fun, I used it to get reqs and break into the top 50 in this test (with boots and glaciate), but it can be a little hard to use and kind of daunting because you have so many options for your moves. I am gonna talk about this one the most because it is the most versatile, so you can customize a lot to suit your needs. If you want to kill defensive cores run expert belt (also lets you bluff jolly band on a supereff hit and adamant scarf on a neutral hit), but I prefer Boots in general right now, since it gives you more health versus Zamazenta. Speed is just to outspeed stuff like max speed Nidoking, you can run jolly if you want to outspeed Urshifu (aqua jet deals a lot but won’t kill) and timid kyurem, I like the power though. You can usually power up punch on a switch to something like toxapex or slowbro. At +1, adamant expert belt victini does 82-97% to pex with bolt strike, and 79.6-94.4% to slowbro. If they want to switch around, once you get to +1 stuff like hippowdon gets cleanly 2ko by v-create. For the record, unaware clef gets two shotted by unboosted v-create, and it’s moonblast won’t do much to you because unaware prevents your sp def drops from v-create from taking effect.
The third slot is a flex slot for a special move or status. I like having a grass move here for the rare but still present gastrodon/quagsire stall on the ladder, not to mention it can be a decent move to midground slowbro just because bolt strike and vcreate pp can become a problem in a longer game. Energy ball is better in general, grass knot is to hit phys def hippowdon the hardest. Glaciate isn’t useful for stall, but you can use it to hit lando, garchomp, or dragapult on the switch and then outspeed them next turn (remember that if it is scarf lando and you are adamant, even after a speed drop they will outspeed you though). Toxic another good option and can be useful to weaken a lot of would be switch-ins, as can will-o-wisp, but since stall runs clerics usually it may not be optimal for that matchup.
Some people like scorching sands, but it doesn’t do that much to sp def heatran, and if you power up punch on the switch to tran, you outspeed and bolt strike will 2KO from there (you live one earth power at full always). You benefit a lot with wish support or slow pivots to keep victini healthy after stomaching a hit or rocky helmet and bring him in safely, and a cleric to cure status from contact can be nice. Be wary of helmet pex with baneful bunker though, I think Ruft screwed me over with his stall team when I played him in a 200+ turn game, setting my req process back like 10 million games >~>
Conkeldurr @ Flame Orb
Ability: Guts
EVs: 252 Atk / 76 Def / 180 Spe
Adamant Nature
- Mach Punch/Drain Punch
- Close Combat/Drain Punch
- Knock Off
- Facade
Prior to the zama test I got a fresh alt to the top 150 on the ladder, with ~81% gxe solely using a team with this mon (if you want the full team check out nyembyuy's post in the RMT forums, it got overlooked but I think it is pretty cool, I modified his evs on Dragapult and Conk a bit but otherwise it's the same, that said I don't recommend it anymore without modification unless Zama stays uber since it gets crushed by zama hard lol), and I've used it on a couple other teams as well.
If you just want to take on walls, drop mach punch, but in the general matchup I don’t recommend it. Even with drain punch, you’re gonna run light on HP fast with this thing so here I highly recommend wish support. Assuming you are burned, facade hits like a truck (98% chance to 2KO max phys def Pex with black sludge if it switches in on Rocks, and a 38% chance to 2KO slowbro by itself, without resorting to Knock Off). CC 2KOs max def tangrowth always (97% chance if it has leftovers), and Knock off into CC always deals 91% minimum to max phys def corviknight (with the standard 168 def spread it is 97.9% minimum, I run enough speed to outrun neutral uninvested corv but watchout for brave bird obviously, even before you get a defense drop). This guy is super volatile so I understand why he isn’t an OU staple lol but bring this in on stall at the right time and it can smash holes.
Nidoking (M) @ Life Orb
Ability: Sheer Force
EVs: 252 SpA / 4 SpD / 252 Spe
Hasty Nature
- Earth Power
- Sludge Wave
- Flamethrower/Thunderbolt/Ice Beam
- Superpower/Taunt
Either just before or just after the mag/ace ban I got 2000+ elo with this set (using flamethrower and superpower). Generally, flamethrower is better in the third slot, but thunderbolt is good for slowking while still hitting birds (Although you lose a neutral move to hit incoming Lando), ice beam hits grounds and zapdos but is very rarely useful vs stall except if its hippo stall. Superpower deals 57.8% min to blissey, and 42.9% min to eviolite chansey, so I recommend bluffing that you don’t have it unless you are sure you are gonna get the kill, people tend to play recklessly with HP on these fat blobs when you hold it back long enough. Hasy Nature is +speed, -def, I prefer that because you want to stomach at least one from slowtwins (and galar slowking) and clef, and I have switched into stuff like Fini moonblast and koko dazzling gleam. Running Mild nature (+sp att, minus def) is viable but I don't generally recommend it unless you really want to dedicate to killing defense with this guy. You can switch freely into clefable lacking knock off (it really sucks to lose orb though so scout for it first, and with toxapex I also recommend scouting it's spread and only using earth power on it when you have a good chance to KO because you don't want to lose orb or get burned when you need superpower). Worth noting that sp def gastrodon and sp def hippowdon (if you don't have ice beam) wall this and are sometimes seen on stall, which is why taunt can be viable over superpower, but often times with a mon as frail as nidoking, if they attack on your taunt it can be a pain, so I usually opt for the attacking move or I will switch out.
Rillaboom @ Life Orb
Ability: Grassy Surge
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Swords Dance
- Superpower
- Grassy Glide
- Taunt
Haven't used this one much myself, but I stole this after Storm Zone beat me with it high in the ladder lol and even with just a few games it has worked well, absolutely monstrous set, I think this one is best suited to hyper offense. You need a bit of prediction here, especially versus corv since he always kills with brave bird after a superpower def drop, but at +2 you deal 68-80% to the standard corv spread, and at +4 you always kill it. Taunt in general is very underexplored in the meta, as okispokis pointed out earlier in the thread. You can choose to either sacrifice this guy in the early game to break big holes or keep it in the back as a grassy glide sweeper like with standard SD rilla once your opponent's defensive mons are weakened a little.
Alakazam @ Life Orb
Ability: Magic Guard
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Nasty Plot
- Psyshock
- Focus Blast
- Encore/Taunt/Thunder Wave
I put this last because out of these 5 I am the least sure about this guy, although I have lost to this unexpectedly before. Alakazam is not super viable in this meta but he is a strong stallbreaker. Having to rely on Focus blast sucks, you can swap for dazzling gleam or maybe shadow ball, but against stall but you want to hit the metal birds really hard. At +2 psyshock always 2KOs kanto slowking (EDIT: earlier I had a typo implying +2 psyshock would one shot slowking, that's not true obviously lol)
, unless it is AV(EDIT2:AV doesn't matter for psyshock lol I'm an idiot). Encore is my best recommendation to beat stall. Catching a corv on a roost is absurd, you basically get a free +2, and for Clef you can encore a calm mind and then spam psyshock. Taunt and T-wave have applications too though. Try this with psychic terrain like in gen 7 to really pump up the body count (specs lele is also a stall murderer but since it is choiced I am not listing it here, and I didn't post taunt magma storm heatran because everyone is aware of that already).
Hopefully this helps you with stall issues, and good luck.