Item: Black Sludge / Leftovers
Ability: Water Absorb
Tera: Ground
EVs: 252 HP / 252 SpD / 4 Def
- Earthquake
- Stockpile / Toxic Spikes
- Toxic / Protect
- Venoshock / Counter
So Black Sludge is very useful, because it will heal Clodsire and if an opponent uses trick they take damage, but if you Tera you will take damage, so pick wisely. Water absorb is to deal with one of its 4 weaknesses. Tera ground for a tera-boosted attack and only weak to grass and ice. Earthquake, as I mentioned, is a tera-boosted attack and a STAB attack. Stockpile for defense boost (even though clodsire has pretty good defense stats) and toxic spikes to deal with some Ice and Psychic types. Toxic is for if you don't pick Toxic Spikes, and Protect is to stall if you do go for Toxic Spikes. Venoshock will deal double damage if the target is poisoned, which can be some STAB. Though Venoshock is a special attack and Clodsire is a physical attacker, I think it is still worth having. Counter is for x2 damage and is a physical move.