I'm going to correct any grammar mistakes from the quote below, just so I don't lose my sanity. I also won't be using calcs since they don't really provide anything that can't just be explained. Now, I suppose I'll get right to it...
- Mega Sableye has significant opportunity cost... ...And on stall, Mega Sableye has so much competition for HP, its insane... ...it's not always easy to make the call to give it to Mega Sableye.
- Mega Sableye has multiple counters, across all playstyles. With impeccable, perfect prediction nothing has counters - but nobody's perfect.
- So what is the actual problem with Mega Sableye? Well... It makes team-buidling harder. Having a whopping four bans in, like, 12 days is kinda extreme. Soul dew, Goth, Chansey and Blissey - although the former weren't supposed to be allowed.
I'll be going point by point and into a fair amount of detail, so bear with me.
"
Mega Sableye has significant opportunity cost... ...And on stall, Mega Sableye has so much competition for HP, its insane... ...it's not always easy to make the call to give it to Mega Sableye."
As it stands now, Mega Sableye has little, to now opportunity cost, or at least any less than other options. Your main argument for this point is that it doesn't let you run other Mega options that could help with different team builds. Well,
no s***. Choosing to run
Mega Sableye over a different Mega Evolution isn't limiting opportunity for a team, that is making a conscious decision to use one Mega Evolution over another. That would be like saying,
"By using [Insert Uber Pokemon] you are limiting your options on Ubers to use." Mega Sableye is simply another option for your Mega slot, and frankly, it is an excellent option for certain teambuilds, and less than optimal for others, which is pretty much how Pokemon works. Now, regarding its competition for the HP stat on Stall teams, not putting Mega Sableye into the HP slot is 80-90% of the time, a really poor decision. No matter what set it is, if it is given the high HP stat on a Stall team, it is
automatically a blanket check to
nearly every Pokemon in the meta. Of course there is an argument for Fairy types, but if that's the basis for why Mega Sableye isn't overtly useful and extremely powerful in the meta, then you're kind of missing the point. With the HP stat and diverse Utilities at its disposal, it provides a major part of the backbone for Stall teams. In fact, Mega Sableye would not be nearly as good of a Magic Bouncer on Stall teams without the large buff in HP because it will get at least 2HKOed by any Atk/SpA boosted threat in the meta. When paired with a strong core, it can shut down almost any team composition; Stall, Balance, Offense, Hyperoffense, etc. When deciding whether Mega Sableye should go into the HP slot for a Stall team or not, it actually is not a difficult call to make. Its Utility options, Set-Up control, Magic Bounce, Recovery, Set-Up options, etc. could not make the decision any easier.
"Mega Sableye has multiple counters, across all playstyles. With impeccable, perfect prediction nothing has counters - but nobody's perfect."
Again, your argument for beating Mega Sableye half revolves around its weakness to Fairy Pokemon. This is nice and all, if you were making a Check/Counter list, but you're also trying to explain why this makes it bad on Stall teams, which is completely inaccurate. That also makes for an illogical argument;
"Mega Sableye loses to Fairy Pokemon, therefore it is not an ideal option on Stall teams." Now, I agree that there are Pokemon that can Check/Counter Mega Sableye beyond Fairy types, especially Poison Heal Pokemon, some of the options you listed are simply incorrect. Beginning with Talonflame, even if it is Bulk Up/Roost Mega Sableye wins 100% of the time if it runs Foul Play. If it runs Toxic, it can simply status and swap into an Unaware Pokemon or any other appropriate switchin. Espeon would be a nice option, if your opponent couldn't simply switch out into a different Pokemon. Being able to set up to +6 Dazzling Gleam on a Mega Sableye is simply a ridiculous proposal. As for Swellow and Pikachu, yes they can Check Mega Sableye, but then again, your opponent can just switch out into their own appropriate Check/Counter and win the matchup. Pretty much every Pokemon listed beyond this is only a Check and your opponent can just switch out and reset the situation, but in the favor of the Stall team. In regards to perfect predictions having no counters, Stall is based on the premise that even if a prediction doesn't work out, the Stall team itself is fine and can recover from any mistake or flub. The point being, you don't need perfect predictions or to even get a prediction correct.
"So what is the actual problem with Mega Sableye? Well... It makes team-building harder. Having a whopping four bans in, like, 12 days is kinda extreme. Soul dew, Goth, Chansey and Blissey - although the former weren't supposed to be allowed."
Addressing the team-building portion really quick, granted that can be said for any good Pokemon in the meta, but Mega Sableye's counters have to be specifically made to beat it. Something like Tyranitar or Rhyperior don't need to only be designed to beat Talonflame and Swellow, they can cover a plethora of other options as well and be extremely proficient in dismantling opposing teams. With the bans, Soul Dew, as you said, wasn't really supposed to be allowed, while Gothitelle's OU-Breaking Shadow Tag was never really addressed until it was decided to simply ban Shadow Tag in general. Chansey and Blissey are also different from really suspecting Pokemon. They were inherently broken aspects of the metagame that were only taken out when their true strengths came to light in this thread.
My short points on Mega Sableye:
- It's far too constricting for teambuilds. Sure the metagame is new and still developing, but when utilized to its full potential and on a great teambuild, especially Stall, it is nearly impossible to beat.
- Its Utility options paired with Magic Bounce are simply too great to ignore; Will-O-Wisp, Toxic, Recover, Knock Off, Foul Play, Calm Mind, Snarl, Dark Pulse, Night Shade, Fake Out, Metal Burst, and Taunt.
- It nearly has the Chansey/Blissey effect to where it is simply one of the best possible options for the HP slot on Stall teams and acts as a blanket check to most of the metagame.