Drilbur's best moveset in Pokémon GO is Mud-Slap and Drill Run, with 10.28 damage per second, and it can deal 121.3 damage before Drilbur faints. This is true when battling in neutral weather.
All Drilbur movesets ranked
Here is a complete list of Drilbur movesets in Pokémon GO, ranked by their DPS and TDO. You can change the weather and the opposing Pokémon.