No, don't even try to argue viability for it, since regular sableye is probably pretty bad to begin with even if you give it void, dbond, pshot, or topsy
... so STABmons Sableye is bad now. What?
The only mega magic bouncer that would likely lead would be mega diancie, which gets hit hard by scald. You also are forgetting that parting shot bounces back onto the user, forcing the opponent out.
I see Mega Sableye lead quite often, and with good reason. Nor am I forgetting the Magic Bounce/Parting Shot point: Parting Shotting out the Magic Bouncer is still spending Starmie's PP
and weakening its ability to smack any other checks you might want to bring in. It's
not opening the way for your setup sweeper to come in, which is what it's
supposed to be doing in this scenario. Priority abusers are in fact
completely safe to come in, in this scenario.
Prankster Misty Terrain? Who would ever use that?
I'm waiting for an actual point.
Mega Venusaur and celebi would probably be uncommon and overpowered in this meta, since a lot of the mons they normally wall get the coverage to beat them. They both hate the uprising of oblivion wing, ice beam, and in the case of celebi, knock off. They certainly aren't misty terrain sableye bad, but they will probably struggle to keep up with the rest of the meta. Furthermore, both are setup bait for parting shot. That is the whole point of using parting shot as a pivot; it neuters the attacker that switches into starmie after it puts something to sleep, which in the case of venu and celebi, only means your switch-in has to come in on a -1 giga drain. Believe me, there are a LOT of sweepers that don't care about that.
... so wait Grass types are straight attackers that always care about Parting Shot. Weren't we talking about Super Effectivemons, rather than Inverse?
Lesse. For starters Mega Venusaur and Celebi both pick up moves for punishing setup sweepers, or turning things around on them. Mega Venusaur can outslow your mad-awesome Shift Gear thing or whatever and use Heart Swap to steal its boosts while dumping Parting Shot's minuses onto Starmie's buddy, while Celebi gains Topsy-Turvy. Which is Topsy-Turvy. Celebi also picks up Quiver Dance to mitigate the effects and make it a potentially threatening sweeper in general too, Dark Void to put your things to sleep, Will O Wisp to Burn Physical types (Making Specially Defensive variants more viable all around), or
it can Parting Shot out of whatever just came in when Starmie Parting Shotted out, completely wasting your effort.
To be "setup bait for Parting Shot" a Pokemon needs to be unlikely to be a problem for what you switch in. You seem to be assuming these Grass types are running their Standard sets, instead of taking advantage of Super Effectivemons movepool gains.
You're also overestimating the relevancy of Oblivion Wing being spread around. It's added to Fighting types (Lucario and Keldeo are the only ones that care), Grass types (So... mirror match?), and Bug types. (Most of which are crap: Volcarona is one of the only ones worth noting) Shaymin-Sky is literally the only Pokemon to gain Oblivion Wing while having STAB on it and actually, you know, giving a crap in all the other relevant ways... and it's banned. (Well, I guess there's Yanmega, but the meta does it surprisingly little in the way of favors) As a coverage move, Oblivion Wing is only 80 BP. That's not some huge deal to Celebi, given it can already tank super effective coverage moves that are stronger than that, and the fact that it lets your setup sweeper heal while attacking is only helpful if you haven't been hit with Topsy-Turvy or something. And anything that gets Tail Glow or Quiver Dance
with Oblivion Wing is a Grass type -so, Celebi itself. Who says you don't Parting Shot out, Celebi Tail Glows, and your setup sweeper dies to
this setup sweeper?
What, Ferrothorn laughs at it? Parting shot to mega sceptile, set up a tail glow, hit in with fire blast / oblivion wing. Easy. You're forgetting that its not putting everything to sleep; its providing the team setup opportunities. By using parting shot on a mon with mediocre coverage/doesn't hit overly hard to begin with, you give setup opportunities to a myriad of threats that gain it.
-1 4 Atk Ferrothorn V-create vs. 0 HP / 4 Def Sceptile: 232-274 (82.5 - 97.5%) -- guaranteed 2HKO
OK. Note that this is Ferrothorn with no investment. Max investment, no Nature boost is a OHKO every time. Hell, Gyro Ball is already more than 50% (At -1 with no investment) against regular Sceptile. And Mega Sceptile. Ferrothorn doesn't even need to use Super Effectivemons moves to kill Mega Sceptile trying to setup like that. It just needs guts and an overconfident opponent.
Or Ferrothorn can run Circle Throw, disrupting your attempt reliably. And it has priority in the form of Mach Punch, to boot.
So yes, Ferrothorn laughs at Starmie.
And why isn't Sceptile running Blue Flare in your scenario? Or Eruption, if we're assuming Oblivion Wing and Giga Drain anyway.
I'm not even going to bother with gourgheist and...cradily? You are pulling up very uncommon mons in saying that they have potential to stop it, but all of them still become setup bait for the proper threat and this will provide an easy pivot to that mon. If you want to continue to argue your point then fine, but there is no point; you're grasping at straws with your argument and seem not to be comprehending Starmie's versatility against things that stop spore.
A year from now, there's going to be a new metagame, you're going to pretend the metagame is OU, and I'm going to, for the millionth time, tell you that the metagame is not OU and viability in OU is not the most important metric for viability in an OM, and to please stop acting like "meh it's underused in Standard/OMs in general" is any kind of argument at all. And then I'll have to repeat it three times to the other people in the thread.
Cradily has picked up King's Shield, Circle Throw, Secret Sword for Special variants wanting to screw over Chansey, U-Turn, Quiver Dance, Sticky Web, Haze, and if it cares about priority Ice Shard and Bullet Punch. It's
already a decent 'mon, and it's gotten tools it actually cares about. Setup variants of it can fuck over phazing attempts by running Suction Cups, too, which is a noteworthy niche when you have Quiver Dance and recovery. Your other options being Octillery (Still no real setup) and Malamar. (Not likely, with its awful typing and fragility)
Gourgeist has picked up
reliable recovery in the form of Roost, the lack of which has always been one of its big flaws, and has been granted Fire coverage for Steel types, which were another nuisance to it. Not to mention Grass types that are immune to its Leech Seed. Smaller boosts, but Gourgeist is pretty solid without recovery in Standard, so it doesn't necessarily
need a lot. Oh, and it gets Insomnia if I went to be an extra jerk and pretend you acknowledged the possibility of running Dark Void, so it can be a hard stop to even that.
And it still gets super effective priority
and Pursuit if you switch
and it can be potentially running Topsy-Turvy for your awesome setup sweeper.
---
In summary: Starmie is a neat gimmick, but you are
overselling it and
underestimating its counters for literally no reason. You've made no effort to actually think about what the counters I named can do, and are instead pretending they're magically helpless in the face of Starmie, because...?
I'm especially annoyed with you yammering on about Oblivion Wing hurting Celebi and playing up setup sweepers while ignoring that Celebi has Tail Glow or Quiver Dance and Oblivion Wing if it wants them. "Celebi is shit because these things exist that it can take advantage of!" is just the most bizarre argument.