Straying away from the theorymon a bit, I'd like to discuss one of the tier's most divisive top-tier offensive threats and one of the most nuanced Tera users right now:
Volcarona. I just finished working on my Offensive Volc analysis (many thanks to the C&C team for their guidance, by the way) and I think there's honestly a lot more to discuss than what a simple analysis can do justice.
The Mon Itself
For well over a decade (feel old yet?), Volcarona's been doing several variations of the same thing: it presses Quiver Dance and then it sweeps if it doesn't bump into a bad matchup. Dubbed the "Matchup Moth" due to its ability to either win a game outright or find itself accomplishing little to nothing, Volcarona has always had its place in OU from its debut in Black and White because it combines the amazing Quiver Dance with its amazing stats, unique typing, strong STABs, good coverage, and excellent utility movepool including reliable recovery to pick and choose its checks and counters. Volcarona's
only real selling point is its access to Quiver Dance, sure, but it's so good at utilizing this move that it could thrive even in the metagames that predated Heavy-Duty Boots, in spite of its crippling 4x Rock weakness.
Volcarona has been a hot topic in OU for pretty much all of its existence because of that "Matchup Moth" title: it has counterplay and it physically cannot circumvent all of said counterplay with a single set (it would most certainly get banned if it could), but it has the means of circumventing individual mons among said counterplay with some tweaks to its moveset and stat investment and if it has the right set for the right occasion it can and most certainly
will sweep a team outright. It's challenging to build a team that handles all Volcarona sets, but it's challenging to build a team around Volcarona in the first place due to the amount of support it requires... well, the latter was much more true prior to the introduction of Heavy-Duty Boots, but Volcarona still needs its teammates to cover the matchups it can't cover.
Volcarona's typing is a mixed bag: it has some shortcomings in that it's weak to Stealth Rock and Rock-type attacks in general as well as Water and Flying, but it's also a Bug-type with a 4x resistance to Grass, a neutrality to Fire, Ice and Fairy resistances, and a resistance to Bug moves including U-Turn while also being a Fire-type that isn't weak to Ground and that resists Fighting. Bug/Fire
really isn't bad. In fact, it's quite a strong defensive typing outside of that brutal Rock weakness. That plus Quiver Dance's SpDef boost plus Volcarona's native Flame Body to punish contact moves collectively make it a mon with quite a lot of good defensive utility despite being a mon with a major defensive shortcoming that it
has to run an item to work around.
How Terastallization Changed Volcarona
Volcarona has always been limited by its coverage and its typing's weaknesses. It has to run Quiver Dance and a Fire STAB is necessary to deal with most Steel-types reliably, but Volcarona had to make a tough choice between Giga Drain, Psychic, and (while the move still existed) a couple of Hidden Power variants. HP Ground dealt with Heatran and some opposing Fire-types, but Psychic dealt with Toxapex and Fighting-types while Giga Drain dealt with bulky Waters. And no matter what set it ran, Volcarona had to feat Rock moves, Water moves, and (to some degree) extremely powerful physical attacks. But Terastallization fundamentally changes Volcarona in every way, offensively and defensively. This gen, Volcarona is debatably better than ever; that's no mean feat when it's so strong in BW OU, has Z-Moves at its disposal in SM OU, and has experienced a massive resurgence in viability in ORAS OU despite finishing that gen as a UUBL mon.
Volcarona doesn't have to play at an inherent disadvantage now that Tera is a part of the equation: offensive sets can expand their coverage with access to newfound STABs in Tera Blast, can buff their existing STABs even further, and can do all this while dramatically changing the defensive profile that Volcarona lives and dies by. And it can do this while still maintaining its niche as a strong Quiver Dance sweeper with a great Speed tier, respectable bulk, and good STABs.
Terastallization is also a countermeasure against Volcarona, though. Most notably, we've been seeing Kingambit and Volcarona playing a sort of cat-and-mouse game of Tera types to try to force an advantage against one-another in SPL. Tera Fire has quickly become one of Kingambit's best options, eclipsing Tera Flying, since it resists Volcarona's STABs and becomes immune to Burns from defensive sets' Will-o-Wisp and all sets' Flame Body. This adaptation to more conventional Tera-Grass Volcarona led to Volcarona adopting new Tera types specifically to beat Tera Fire Kingambit. The big one, of course, is Tera Ground alongside Tera Blast. Everyone expected this to be amazing in a meta with Heatran, but we aren't there yet; but Tera Ground Tera Blast still maintains a strong hit against Clodsire, Toxapex, and most opposing Fire-types. Tera Flying Kingambit can handle Tera Ground Tera Blast, sure, but it has to play a dangerous game of risking a Burn against other Volcarona sets.
Breaking Down the Tera Type Index:
Volcarona is not one-dimensional in its abuse of Terastallization, as the official Tera Type index reflects. To briefly go over what each of Volc's many, many,
many Tera types do:
The Common Tera Types:
- Grass, ft. Giga Drain: Grants Volcarona a crucial Ground resistance and gives it STAB Giga Drain. When run alongside Substitute and Giga Drain, Volcarona can PP Stall Clodsire's Recovers and outheal Substitute's damage thanks to that Earthquake resistance.
- Ground, ft. Tera Blast: Turns Volcarona's major Rock weakness into a resistance, gives Volcarona an Electric immunity, and grants Volcarona a powerful STAB that handles Iron Moth, Clodsire, Toxapex, and most Fire-types including the aforementioned Tera Fire Kingambit designed to handle most Volcarona variants.
- Fairy, with and without Tera Blast: It's a generally great defensive typing, especially on defensive sets with Wisp, but I actually think that Tera Fairy+Tera Blast on offensive sets deserves special mention as an underrated tech. I brought this up in my Analysis as a means of handling Dragon-types like Baxcalibur, Dragapult, Dragonite, and Garchomp, and I think this is very unexplored at the moment despite having a very real niche of taking out some of Volcarona's scarier offensive checks. Dragapult and Dragonite are very relevant targets, after all. Give this one a try!
The Situational (But Still Good) Tera Types:
- Bug/Fire: Lumping these in together. Volcarona already has some pretty formidable STABs, so buffing them even further is always an option. Volcarona's typing as a whole is quite synergistic defensively, but getting rid of some of the dual typing's shortcomings can be useful. Removing its Water weakness with Tera Bug or its Flying weakness with Tera Fire has some situational defensive merit.
- Psychic, ft. the move Psychic: Clodsire is much more threatened by Tera Psychic+Psychic, as it's a solid 2HKO. Volcarona can use this to muscle past many Skeledirge variants, and it maintains super effective hits against Fighting-types like Quaquaval and Iron Hands while still hitting Pex and Clodsire. There's a use case for Life Orb on this, and it might even be usable on Indeedee Psychic Terrain teams? It's still a good option in general.
- Steel: Turning your mon into Registeel is kinda neat. A Poison immunity and Steel's amazing defensive profile can give Volcarona a lot more opportunities to set up a Quiver Dance or two.
- Water: Turning your mon into Suicune iskinda neat. Newfound Water and Fire resistances and a generally-good defensive profile help Volcarona set up more easily. Maybe Tera Blast is worth considering to hit Fire-types (including opposing Volcarona) and Clodsire?
- Rock, ft. Tera Blast: "I used the Volcarona to destroy the Volcarona." Hits Fire-types, Dragonite, and Baxcalibur very hard so it's more than just an anti-Volc tech, but if there's one thing Volcarona appreciates it's the opposing Volcarona being removed after the two engage in a Quiver Dance war that would typically depend on one of them critting the other.
In Short:
Volcarona is
extremely polarizing right now, and for good reason. This is the first time in a very long time that the esteemed Matchup Moth can win pretty much all its bad matchups, albeit not with a single set, and the sheer unpredictability of Terastallization as a whole is put on full display with Volcarona specifically since it has a bare minimum of
nine viable Tera types. Hell, I even think there's room for stuff like Tera Flying+Hurricane or Tera Electric should the metagame shift in that direction. But I can't help but feel as though it warrants more discussion than just "is it problematic?" since Volcarona, for how polarizing it is, has a lot of room for nuance and expression right now. I was very surprised to find that Tera Fairy+Tera Blast wasn't talked about a lot, but I opted to include it as a viable option on an offensive set because of how much potential merit it has offensively for how good it is defensively, and I quite like its role in this tier despite it being something to keep an eye on.
Discussion Points:
I'd like to propose a series of questions to anyone who would like to answer any or all of them:
What's your favorite Volcarona set right now? Bulky, 3-Attacks Offensive, Sub+Giga Drain, etc.
What Tera type do you prefer on your Volcarona sets?
What Tera type Volc could or does utilize well do you think is being underrated right now?
What teammates do you like running with your Volc currently?
If you build teams that Volc doesn't fit on, what are you running to keep its many sets in check?
blocks 
from defogging
does actually learn it, I haven't actually tried, and it sounds like a cheese meme set, but hey, maybe you can have some fun with it
Whirlwind Iron Moth sounds like one hell of a thing to pull off. I've been using Dragon Tail Walking Wake with Expert Belt and it confuses the hell out of my opponents. I LOVE it.
was a mon most famously appearing on stall teams, yet he is not a passive mon, it just so happens that he has the correct tools to help stall by tenfold
for example in my book is not passive because Hyper Voice + 110 SpA + Pixelate, but many people call it passive due to her only being viewed as a Wish Pass mon
is a generally passive mon that only runs moonblast, what makes clefable insane its her insane durability, recover, magic guard, big ass move pool, meaning that, while not dishing damage it still doing stuff. But clef CAN potentially be active if given the correct set for it
from gen 7 to gen 8 was technically passive in a sense that she only could spam Scald/Knock Off and stuff like toxic/Tspikes and haze/recover, yet scald alone made pex a burn generator, so it went from passive to ban worthy in multiple times, but this is a Scald thing and not a pex thing, prooff of this is gen 9 where pex is significantly less useful because it can hide from its status as a true passive mon anymore
is a truly passive mon, where her offensive capabilities are so trash that you need Seismic Toss
