Pecharunt @ Life Orb / Black Sludge
Ability: Poison Puppeteer
EVs: 4 HP / 252 SpA / 252 Spe
Tera Type: Poison / Ghost
Modest / Timid Nature
- Malignant Chain
- Shadow Ball / Hex
- Recover
- Nasty Plot
88 Base special attack isn't great, so personally, I'd go Modest combined with Life Orb to guarantee an OHKO, but you can go Timid or Black Sludge (probably put some more EVs into bulk though, if you're running Black Sludge) Malignant Chain, because it's just a good move, 20% for BADLY poisoning and 100 base power with no drawbacks? Sludge Bomb is easily the second option though. You can run Shadow Ball or Hex, Hex if you plan on poisoning, Shadow Ball if not, and lastly, Recover is just a good move, and Nasty Plot is special Swords Dance, so it's naturally overpowered.
This is a big glass cannon set though, so if you prefer more bulky mons, look elsewhere. Also, I'm no Wolfe Glick, while I do have some competitive knowledge, I'm not an infallible genius.