Fidough's best moveset in Pokémon GO is Bite and Play Rough, with 7.55 damage per second, and it can deal 95.3 damage before Fidough faints. This is true when battling in neutral weather.
All Fidough movesets ranked
Here is a complete list of Fidough movesets in Pokémon GO, ranked by their DPS and TDO. You can change the weather and the opposing Pokémon.