This thing is absurdly powerful, no doubt about that. There is a set I've been running that is the anti-christ in terms of stall. This set originated out of seething hatred for Roobushin, and since then it's been used for much more:
Rankurusu @ Life Orb
Ability: Magic Guard
EVs: 252 HP / 252 Def / 4 SpAtk
Nature: Bold (+Def, -Atk)
~ Calm Mind
~ Recover
~ Psycho Shock
~ Focus Blast/HP Fighting
Right off the bat, this thing has 424 HP / 276 Def / 203 SpDef, making it amazingly bulky, being able to avoid a OHKO from almost everything unboosted. Blissey and friends becomes setup bait for Rankurusu, as it boosts in the face of status, which does jack shit to it, and then slays EVERYTHING with Psycho Shock or FB/HP Fighting, which nearly achieves perfect coverage. Sure, Psychic types can resist it's moveset, but most either have a secondary typing that affords it a neutrality to either move, or they're not strong enough to KO this thing. It can also set up on some weaker threats as well. Notably, after a CM, HP Fighting OHKO's Tyranitar, which TTar fails to do back, although CB Crunch might OHKO. You need Psycho Shock since otherwise CMers like Suicune can beat you outright, at a cost of having issues taking on Roobushin.
Really, if you need a stallbreaker that isn't Gliscor, this guy is amazing.