Arcticblast
Trans rights are human rights
Technically, Groudon has a lot of competition - in reality, Eviolite Rhydon is the physically bulkiest Pokemon in the game if you're going by stats alone.Funny you mention Landorus Therian, as Lando is pretty much a better physical wall than Gliscor.
With a spread of 200 HP/64 Atk/244 Def, Adamant Nature, and a pokemon Intimidated, Landorus has physical bulk comparable to Groudon. Yes. The greatest physical wall in the game, Lando T can compare itself to.
-1 252+ Atk Choice Band Dragonite Outrage vs. 200 HP / 244 Def Landorus-T: 187-222 (50.67 - 60.16%) -- 85.94% chance to 2HKO
252+ Atk Choice Band Dragonite Outrage vs. 72 HP / 4 Def Eviolite Rhydon: 187-222 (50.67 - 60.16%) -- guaranteed 2HKO
Those EVs might seem weird, but they give Rhydon the same exact HP and Defense stats as Landorus-T. If you're looking for something more, check this out:
252+ Atk Choice Band Dragonite Outrage vs. 252 HP / 252+ Def Eviolite Rhydon: 141-166 (34.05 - 40.09%) -- guaranteed 3HKO
Even max/max Impish Groudon takes 46.28 - 54.95% from that.
If you're factoring in typing, there's probably a better Steel out there.
Landorus-T's sole ability is Intimidate. It can have no other ability. It has a bit of trouble setting up because of its common weaknesses - if it doesn't set up a Rock Polish quickly, a KeldeoIt almost single handely destroyed Drag2Mag teams (at least physically based dragons, special based ones had to eat a U-Turn as Latias, Hydreigon, and Latios are all weak to it), sets up rocks, can sweep potentially with an RP boost (427 attack and 562 speed after a Rock Polish is no joke), can run an EXTREMELY effective Double Dance set, or can even go Sheer Force and become a surprise special attacker (inferior to Landorus Incarnate in this area though).
AcroBat suffered a huge loss in viability with the banning of Sand Veil. It isn't exactly "awesome."Gliscor can stay where it is. While it stalls pretty well and can run that AWESOME AcroBat set, thats all it can do. As a physical wall, Landorus Therian outclasses it.
All of the above said, while Gliscor and Landorus-T operate slightly differently, Landorus-T is almost always superior. The only reason to use Gliscor over Landorus-T is for a Toxic stalling set, which it does admirably. It loses to Pokemon with Substitute if it can't outspeed them, however.