I've been having success with this set:
Absol @ Absolite
Ability: Justified
EVs: 252 HP / 252 Def / 4 Spd
Bold Nature
IVs: 0 Atk
- Calm Mind
- Baton Pass
- Thunderbolt
- Fire Blast/Will-O-Wisp
You may think I'm crazy, but this set works remarkably well. For starters Klefki, Sableye, Mandibuzz and Ferrothorn can't do a damn thing back and become complete set up fodders, especially if you burn them:
0 Atk Mandibuzz Foul Play vs. 252 HP / 252+ Def Mega Absol: 59-69 (17.6 - 20.6%) -- possible 5HKO
4 Atk Ferrothorn Power Whip vs. 252 HP / 252+ Def Mega Absol: 121-144 (36.2 - 43.1%) -- guaranteed 3HKO
4 Atk burned Ferrothorn Power Whip vs. 252 HP / 252+ Def Mega Absol: 60-72 (17.9 - 21.5%) -- possible 5HKO
This Absol can also absorb the omnipresent and obnoxious Knock Off with little consequence:
252+ Atk Life Orb Bisharp Knock Off vs. 252 HP / 252+ Def Mega Absol: 73-86 (21.8 - 25.7%) -- 2.5% chance to 4HKO
If Azumarill, Mega Mawile or Togekiss try to switch on this they either get 2HKO'd by the appropriate move or crippled by WoW. If Clefable or Sylveon switch in you Baton Pass to an appropriate check/counter. Ditto for Conkeldurr - even if you burn it on the switch you can live a Mach Punch if it's running Assault Vest:
252+ Atk Guts Conkeldurr Mach Punch vs. 252 HP / 252+ Def Mega Absol: 224-266 (67 - 79.6%) -- guaranteed 2HKO
You can run other special attacks like Dark Pulse or Ice Beam, but Thunderbolt and Fire Blast hit most of Mega Absol's switch-ins for SE damage.
You can also forego Baton Pass but not running it is kind of a waste since it has Magic Bounce.
Oh and this set completely nullifies SwagPlay teams, which is nice if you're battling on the suspect ladder.
Finally this Absol can also deal with Baton Pass teams if you run Perish Song (obviously don't run Baton Pass if you do).
Edit: Justified might be counterproductive on this set if you're trying to take as little damage as possible from Foul Play, but it can be useful with Baton Pass. If you're not running BP then run Pressure instead.