Would anyone care to have a look at this Cofagrigus I was going to try using in VGC?
Cofagrigus @ Leftovers
Ability: Mummy
EVs: 252 HP / 4 Def / 252 SpD
Calm Nature
IVs: 0 Atk
- Pain Split
- Curse
- Rest
- Sleep Talk

Maximum Special Defense investment allows him to shrug off all but the most powerful neutral special attacks, and survive many SE ones.

252+ SpA Aegislash-Blade Shadow Ball vs. 252 HP / 252+ SpD Cofagrigus: 116-140 (70.3 - 84.8%) -- guaranteed 2HKO after Leftovers recovery

252 SpA Choice Specs Hydreigon Dark Pulse vs. 252 HP / 252+ SpD Cofagrigus: 140-168 (84.8 - 101.8%) -- 6.3% chance to OHKO

252 SpA Mega Charizard Y Overheat vs. 252 HP / 252+ SpD Cofagrigus in Sun: 136-162 (82.4 - 98.1%) -- guaranteed 2HKO after Leftovers recovery

Then take into account that it's fairly common to run wonky EV spreads to survive specific attacks and he's pretty solid when it comes to special bulk.

I decided to forgo Defense investment as he is already physically bulky enough as it is, few physical attackers like losing their ability to Mummy, and most spread moves that might hit him aren't powerful to phase him due to the amount of recovery he has.

This set's goal is essentially to be an extra powerful version of sandstorm/damaging status, chipping away at enemies with Curse and Pain Split, while staying healthy with Leftovers, Rest and the recovery provided by Pain Split. Hopefully finishing off enemies that may have survived another turn at low health or forcing threats to its partner to switch out to shake off curse.