Volcarona @ Heavy-Duty Boots
Ability: Flame Body
EVs: 252 SpA / 4 SpD / 252 Spe
Modest Nature / Timid Nature
IVs: 0 Atk
- Quiver Dance
- Flamethrower
- Bug Buzz
- Psychic
Given that SD Rillaboom fits primarily on Hyper Offense teams, it's only fitting that it finds a good partner in another HO pick in Volcarona. QD Volcarona does an excellent job of pressuring, setting up on, and eliminating the bulky Steels and Grasses such as Ferrothorn, Corviknight, Kartana Skarmory, Mega Scizor, Amoonguss, Tangrowth, and Mega Venusaur that can halt the grassy gorilla in its tracks. In exchange, Rillaboom serves to eliminate the few things that can stop this Volcarona set such as Chansey/Blissey, Garchomp, and Heatran, as well as providing an excellent option to revenge Volc revengers like Ash Gren, Medicham-Mega, and Lop-Mega
In addition, Rillaboom's Grassy Terrain gives Volcarona not only passive recovery, but also an excellent, albeit temporary stopgap vs dangerous Ground types.
In terms of the set, Modest is chosen here because both SD Rilla and offensive Volcarona tend to fit excellently on Screens HO which, thanks to its ability to further bolster their bulk, gives Volc more chances to set up, so the speed loss isn't too terrible and Modest gives a more immediate, threatening power boost. Timid should be used off of Screens however. As for the last move, Psychic is used to pressure both Toxapex and Kommo-o, the latter of which otherwise serves as an excellent check to both of them.