Shadow Weedle's best moveset in Pokémon GO is Poison Sting and Struggle, with 4.19 damage per second, and it can deal 21.2 damage before Shadow Weedle faints. This is true when battling in neutral weather.
All Shadow Weedle movesets ranked
Here is a complete list of Shadow Weedle movesets in Pokémon GO, ranked by their DPS and TDO. You can change the weather and the opposing Pokémon.