Where to Find and Catch Volcarona
From Pokemon Go Wiki
Volcarona are found and captured in Nest and Habitat locations.
Nests
Volcarona Nests are locations that consistently spawn Volcarona.
Habitats
Volcarona Habitats are spawn locations where Volcarona is likely to be encountered, but not guaranteed the way a Nest is.
Additional Tips and Information
Best Nests
If you know a really good nest or any of the nests above is really good, list them here: