While the Bug type has been long lamented as one of the worst of the game, Volcarona has risen above such allegations to near legendary status. Most apparent about Volcarona is its power. Base 135 Special Attack is literally legendary and Volcarona can make excellent use of that with its fantastic Bug + Fire STABs and several coverage options allowing Volcarona to raze everything in its path. Volcarona's decently fast too, base 100 Speed the gold standard for the longest time and Volcarona itself helped cement this as this standard. What pushes Volcarona over the edge offensively is Quiver Dance, one of the most powerful setup moves in the game. Calm Mind with a Speed boost on top allows Volcarona to escalate out of control incredibly quickly, and can take over games on the spot if given the chance.
Yet Volcarona in VGC is just as valued for its supportive merits as much as its offensive ones. Indeed, in the most powerful formats, Volcarona is a supportive staple, making excellent use of Rage Powder to protect allies and disrupt setup strategies. Rage Powder is also particularly damaging to physical attackers thanks to Volcarona's Flame Body, allowing a lucky Burn to neuter their threat level for the rest of the match. Flame Body is far from Volcarona's only form of damage mitigation either, with access to Struggle Bug and Will-O-Wisp to cut down special and physical attackers. Add in Tailwind for potent Speed control and Volcarona can do it all, especially when you consider its offensive sets are just as viable, allowking Volcarona to fulfill many a team's needs. Even at Volcarona's most defensive, it is still a Volcarona with all the power that implies, its Fire and Bug STABs invaluable in striking down the many popular Grass and Psychic type support pieces found on every team. Really the only thing stopping Volcarona from seeing even more play is its paltry Defense allowing physical attackers to remove it rather quickly despite the risk of Flame Body.
Strike the Sun
-Rage Powder
-Will-O-Wisp
-Fiery Dance
-Protect
Ability: Flame Body
Item Attached: Rocky Helmet
EVs and Nature:
252 HP / 196 Def / 60 SDef
Bold Nature
Tera Type: Water/Grass
Supportive Volcarona is a menace in VGC and for good reason, with this set explicitly out to ruin Urshifu-Rapid's day. Rage Powder with a Water resistant Tera heavily punishes Surging Strikes with multiple activations of Rocky Helmet and multiple chances for Flame Body often leaving Urshifu in a worse position than Volcarona after the attack, while Volcarona's Fighting resistance pre-Terastlization offers some delicious mind games. Will-O-Wisp removes the luck aspect of Flame Body from the equation, ensuring Volcarona can cripple physical attackers like Urshifu, Iron Hands, Zacian-Crowned, Zamazenta-Crowned, Rillaboom, non-Hearthflame Ogerpon, etc. Fiery Dance ensures Volcarona isn't entirely passive and in fact can capture some of the magic of its offensive varients with a few lucky rolls allowing Volcarona to escalate out of control, while threatening prominent Fire weak targets like Zamazenta-Crowned, Zacian-Crowned, Rillaboom, Whimsicott, Amoonguss, Calyrex-Ice Rider, Chien-Pao, etc. Protect is the best move in Doubles, and Volcarona is a rare Pokémon less bothered by Urshifu's Unseen Fist given Urshifu doesn't like risking the Flame Body burn and Volcarona's natural resistance to Fighting STAB.
EVs are to heavily increase Volcarona's physical bulk to better handle the physical attackers it is meant to shutdown. Water resistant terastalizations are mandatory in order to ruin Urshifu Rapid. Tera Water is an amazing defensive type in general, though Tera Grass has several of its own merits. With Tera Grass, Volcarona stifles Amoonguss and Smeargle's Spores, while ignoring their own redirection and doesn't leave Volcarona vulnerable to Rillaboom's Grassy Glide. However, Grass' many weaknesses including the shared weakness to Flying that Tornadus and Acrobatic Roaring Moon are more than happy to exploit prove Tera Water's own merits.
Preferred Partners:
Calyrex Ice Rider loves Volcarona's support, given Volcarona's incredible matchup into general anti Trick Room mon Amoonguss, along with Volcarona handling difficult matchups in Zacian and Zamazenta Crowned and generally making Calyrex Ice Rider bulkier with Will-O-Wisp and Struggle Bug support. Volcarona doing well into opposing Calyrex Ice Rider is another bonus.
Electric types like Miraidon and Raging Bolt make for excellent partners to Volcarona, handling the Water and Flying types that can quickly remove Volcarona, while Volcarona effortlessly dispatches troublesome Grass types like Amoonguss and Rillaboom that soak their Electric STABs. Both Miraidon and Raging Bolt love the Speed control and damage mitigation Volcarona provides, keeping them around longer and making them that much more dangerous.
Ironically Urshifu Rapid also works well with Volcarona, loving the Tailwind support, and forming a solid Water-Fire core.
Other Options:
Struggle Bug is the special damage answer to Will-O-Wisp's physical, and Volcarona still maintains its burn capability with Flame Body.
Tailwind is the best Speed control method around and Volcarona's stands out as a bulky setter.
Giga Drain keeps Volcarona around longer and further ruins Water types, though it can be hard to fit space for it.
Overheat is excellent for picking up sudden KO's out of nowhere and support Volcarona is less bothered by the Special Attack drop given its primary role isn't damage.