Very true Resto Chesto volc is pretty threatning but SR really hampers it's day. Besides the fact that it is Resto Chesto (Rest/QD/Bug Buzz/Fire Blast) means Heatran Walls it for days on end even more so if it's the SpD Tran. w/SR and Roar in it's move slot Volca won't be doing much of anything...
Not that I think Dnite isn't a big threat but I think you're hyping him up way too much.
252 +1 Atk Dragonite Fire Punch vs 252 HP/252 Def Skarmory: 47.31% - 55.69%
2-3 hits to KO (with Leftovers)
252 +1 Atk Dragonite Outrage vs 252 HP/252 Def Hippowdon: 50.24% - 59.52%
2-3 hits to KO...