AB: Sturdy (for Survival against fire and steel types)
Nature: Jolly/Adamant (Skarmory needs more Speed and he has no use for Sp Attack, Adamant if you want Attack instead of Speed)
Drill Peck (Good Dmg, High Accuracy, STAB + lots of uses)
Steel Wing (Good Dmg, ok Accuracy, STAB + Chance of Defence Boost)
Swords Dance/Autotomise (for attack or Speed Boost depending on what you think you need)
Roost (for healing and remaining Sturdy)
Good and nice Moveset for Skarmory, not exactly the most tactical moveset but good for slaying mostly everything XD, the Leftovers and roost helps keeping the Sturdy intact and helps you to come to Attack/Speed (Swords Dance/Autotomise +8 pretty easy and still remaining at mostly full hp if you do it right.