Not sure I did the calcs right, but assuming Heatran switches in and you Quiver dance while he does so, you can actually set up on Heatran (barring stone edge) with Quiver Dance and Morning Sun and then kill it with a 6+ Bug Buzz and proceed to sweep, although you will need reasonable investment if the Heatran is Modest and has Choice Specs (though Choiced fire is set-up fodder for other stuff, and could be taken advantage of).
Obviously, Explosion ruins this, but that removes Heatran from play as well. I'm starting to like this set.
Edit: just ran another calculation - with HP investment but not sp.Def investment, after two Dances, Volcarona will never take more than 50% from Modest Specs Heatran Fireblast, allowing it to Dance again, call in morning sun and set up. With the same set up, it will never be 2HKOd by Eruption if Volcarona has leftovers and also be able to set up.
Obviously, Explosion ruins this, but that removes Heatran from play as well. I'm starting to like this set.
Edit: just ran another calculation - with HP investment but not sp.Def investment, after two Dances, Volcarona will never take more than 50% from Modest Specs Heatran Fireblast, allowing it to Dance again, call in morning sun and set up. With the same set up, it will never be 2HKOd by Eruption if Volcarona has leftovers and also be able to set up.