Hasty Raikou's guru
IMO, DDMence is a bad choice because of Salamence's common weaknesses to spread moves like Blizzard and Rock Slide. A Mixed Scarf set would work better with HP Flying, Draco Meteor, Rock Slide and Flamethrower. You probably want enough Attack to OHKO 4 HP Volcarona with double-target Rock Slide which I think is 36 Attack (idk which nature atm...)
And btw, i think that the right nature for your suggested set may be Rash; and i'll try it too.