Gliscor falls in an odd range which it a decent wall, but not a phenomenal one. I know, for example, that Gliscor is sometimes just barely is unable to stop something like Dragonite from sweeping if barring down on it and sweeping the team, while something like Hippowdon can stop it without a doubt, the defensive edge matters.
252+ Atk Choice Band Dragonite Outrage vs. 252 HP / 252+ Def Celebi: 237-280 (58.6 - 69.3%) -- guaranteed 2HKO
252+ Atk Choice Band Dragonite Outrage vs. 252 HP / 252+ Def Gliscor: 204-240 (57.6 - 67.7%) -- guaranteed 2HKO
Its tankier than Celebi, so that's saying something. Not a lot of things are as tanky as Hippowdon (who is damn near Lugia in terms of physical walling potential), but Gliscor is still a solid wall... especially since it heals 12.5% each turn instead of 6.25%. That bit of extra healing adds up to a lot of sponging.
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Anyway, speaking of "stall", what about Mega Tyranitar ?? Sets stealth rocks, sets up sandstorm, it will be like GSC TSS strategies of old, except TTar doesn't need to run Sandstorm.
Lets look at some calcs, right?
252+ Atk Choice Band Dragonite Outrage vs. 252 HP / 252+ Def Mega Tyranitar: 178-211 (44 - 52.2%) -- 16.8% chance to 2HKO
252+ Atk Choice Band Dragonite Outrage vs. 252 HP / 252+ Def Hippowdon: 211-250 (50.2 - 59.5%) -- guaranteed 2HKO
Physically, Mega-TTar has more bulk than Hippowdon. (although Hippowdon will have leftovers and slack-off). In Special Defense, Mega-TTar has much much more, even outside the sand.
252+ SpA Hydreigon Draco Meteor vs. 252 HP / 0 SpD Hippowdon: 297-351 (70.7 - 83.5%) -- guaranteed 2HKO
252+ SpA Hydreigon Draco Meteor vs. 252 HP / 0 SpD Mega Tyranitar in Sand: 130-154 (32.1 - 38.1%) -- 96% chance to 3HKO
I'm theorymoning here, but I think Mega-TTar is going to be the premier mega for Stall Teams. Sandstorm is ever so important source of passive damage and Rock-pokemon Sp. Defense, TTar has easy access to Stealth Rocks.
TTar also has access to Roar / Dragon Tail and Stealth Rocks. So it can most certainly shuffle enemies around. You'll probably want someone with actual recovery to do that job however... but you're still looking at a `mon with 164 Attack and 700 BST. Surely it can do _something_ in stall, right?
Remember: TSS was a strategy before Sand Stream even existed. Sand Stream may be nerfed now, but it ought to be possible to run a stall-game using only normal Sandstorm as an attack. Granted, wallbreakers weren't as strong back then, and rapid spin didn't exist... but the theory is still sound IMO.
Having both Hippowdon and Mega-TTar as Sandstream users will help out sand-stall teams greatly.