Doubles Toxic Chain Abuser
Fezandipiti @ Ability Shield
Ability: Toxic Chain
Tera Type: Fairy / Dragon
EVs: 252 HP / 252 SpA / 4 Spe
Timid Nature
- Protect
- Dazzling Gleam
- Acid Spray / Venoshock
- Icy Wind / Heat Wave / Air Cutter / Tailwind
The whole idea with this set is to exploit Fezandipiti's absolutely BUSTED ability, Toxic Chain, in double battles. Basically, if Fezandipiti hits another Pokemon with an attack - not even a contact move, just an attack - it has a 30% chance to badly poison the target. Sure, all three members of the Loyal Three have this, but Fezandipiti has some pretty great spread moves to take advantage of that fact, which more than makes up for its weaker Special Attack, in my opinion. In fact, with a spread move like Dazzling Gleam, there's a 51% chance you badly poison at least one of your two opponents, assuming neither already has a status condition, and a 9% chance to badly poison both opponents in one go.
The main idea here is to pair Fezandipiti with a Neutralizing Gas Weezing. Weezing gets rid of your opponents' abilities, but with its Ability Shield, your Fezandipiti's Toxic Chain will remain just fine, totally unaffected. Which allows you to go to town. Protect is Protect (and with Weezing, not even an Urshifu can hit you) and it can help stall once you have a poisoned opponent on the ropes. Dazzling Gleam is a strong, STAB spread move, and your strongest attack with this set. Acid Spray is single-target, but the sharp Special Defense drop improves your team's offense. Venoshock is a bit more niche, but to a poisoned foe, you're hitting with a 130 base power STAB attack. These single-target moves also keep you from being completely walled by Wide Guard. The other three moves are all spread moves and coverage, with a few added effects. Icy Wind is the most valuable, offering Speed control, Heat Wave may burn a foe (bringing your odds of inflicting a status condition to at least one of two foes up to 60.31%) and Air Cutter has a heightened crit chance and is super effective against Ogerpon (except Cornerstone). Tera Fairy ups what little damage you do with Dazzling Gleam, while Tera Dragon offers some helpful resistances to Ogerpon (again, except Cornerstone). You can also run Tailwind for a more supportive role.
Sources:
https://bulbapedia.bulbagarden.net/wiki/Toxic_Chain_(Ability)
https://www.calctool.org/math-and-statistics/probability