Here's a bit of a bulkier Volcarona set. (Well, bulky by Volocarona's standards)
EVs: 252 HP, 252 Defense, 4 Speed
-Fiery Dance/Flame Thrower/Fire Blast
The idea of this set is for Volcarona to be able to withstand some physical hits, and set up with Quiver Dance to be able to take Special attacks while gaining Speed and Special Attacks. Volcarona's ability to take physical hits is even further added to by its ability, Flame Body. Leftovers allows for some HP recovery and more sustainability, whereas Lum Berry would allow for a free Quiver Dance if an opponent tries to hit you with a status. Of course, Bug Buzz and your Fire type move of choice are obvious moves. HP Rock is possibly one of the best Hidden Powers for Volcarona, hitting pokemon such as Gyarados and fire types for super effective damage.
If you want to use this set, having a Rapid Spinner on your team is almost necessary, because stealth rock completely defeats the purpose of this set