Its kind of gimmickly but its a set you can use for doubles triples in something with trick room or straighly in trick room team, your choise.
Seviper @ Black Sludge / Leftovers (leftovers depend of your team)
Ability: Infiltrator
EVs: 252 HP / 252 Atk / 4 Def
Adamant Nature
- Final Gambit
- Protect
- Poison Jab
- Earthquake / Knock Off / Aqua Tail
The idea its get a final shot in something big, you can protect for trick room to make its easily.
If you can kill someting with STAB go agead and smash it. The final slot its coverage, knock off for psiquics, aqua tail in ground and EQ its to hit super effective hits in common counters like steel or poison.
You can try this set in the speacial side with moves like sludge bomb and giga drain, dark pulse or flamethrower for coverage, all in a modest way.