Att would be his best. HP, Def and Sp Def should be as high as possible. Speed as low as possible (he/she must attack last, Brave nature helps) and Sp Att doesn't really matter.
For a hold item I'd say either a Lum Berry (prevent status conditions) or Leftovers (it still gets hit sometimes, this way you can save yourself some damage). --- 3DS FC: 2836-0413-5340 PM me with your FC if you added me.