What it does
Bug Buzz is a Bug-type special move with reliable damage and roughly a 10% chance to drop the target's Special Defense by one stage. It hits a single target, not both opponents. If the SpDef drop fires, it immediately benefits any follow-up special hits from your partner that same turn.
One hard mechanic to know: Bug Buzz is a sound-based move. Pokémon with Soundproof are completely immune — no damage, no SpDef drop, nothing. If you click Bug Buzz into a Soundproof target, you waste the turn entirely. Check your opponent's abilities before committing.
Who runs it
Volcarona at 20% usage. Bug hits Psychic and Dark types for 2×, which complements the Fire-type coverage that makes up the rest of Volcarona's offensive toolkit. The 20% figure being lower than its Quiver Dance usage (45%) tells you Bug Buzz is a coverage decision made during team building, not an auto-include.
How to use it
In doubles, Bug Buzz is your coverage move when the target resists Fire but is weak to Bug. Psychic-type targets are the main scenario. The SpDef drop isn't something you can rely on, but when it lands and your partner has a special attacker on the field, the combined damage in the same turn is noticeably higher.
Bug Buzz versus Fiery Dance is essentially a question of target type. Fiery Dance has broader coverage and the chance to boost your own SpAtk, making it the more common choice. Bug Buzz is the specific answer to Psychic and Dark types that Fire can't deal with cleanly.
Tips & strategy
After a Quiver Dance, Bug Buzz hits harder and the value of the SpDef drop increases — if the drop triggers on a boosted Bug Buzz, your next attack will deal noticeably more. That's the ideal sequence: Quiver Dance turn, then Bug Buzz plus a partner's special attack, with the SpDef drop amplifying both.
If your team already has other ways to threaten Psychic-type targets, Bug Buzz competes for the same slot. At 20% usage, plenty of Volcarona builds opt for something else in that move slot — the decision comes down to what your team needs.