Joltik @ Eviolite
Ability: Unnerve
EVs: 196 HP / 220 Sp. Atk / 76 Spe
Timid Nature
Thunderbolt / Electro Ball - STAB
Bug Buzz - STAB
Giga Drain - Coverage
Thunder Wave - Setup
The Eviolite is to boost it’s poor defense and Sp. defense. Unnerve is to stop the opponent from eating their berries. The EVs in Hp boost its HP, same for Sp. Atk, and Spe.
The Timid nature is to boost it’s speed. Thunderbolt is a good move with STAB boost. You could also use Electro Ball, but that isn’t as reliable as Thunderbolt. Bug Buzz is also STAB damage. Giga Drain is to recover HP, as well as have a good coverage move. Thunder Wave is to paralyze the opponent, which would be better for Electro Ball.