I prefer Mandibuzz running 248 HP / 252 Def / 8 SDef on Impish nature, with the moves Foul Play, Roost, Knock Off, and either Defog or Taunt based on what your team needs. I personally prefer this over a Specially defensive because its typing isn't built to take Special attacks; a considerable amount being BoltBeam (Ice/Elec), and no amount of investment can prevent KOs from them.
248 HP instead of 252 HP for an odd amount of HP, so you take 24% from Stealth Rock instead of 25%, since it rounds down.