Tepig's best moveset in Pokémon GO is Tackle and Flamethrower, with 8.16 damage per second, and it can deal 100.8 damage before Tepig faints. This is true when battling in neutral weather.
All Tepig movesets ranked
Here is a complete list of Tepig movesets in Pokémon GO, ranked by their DPS and TDO. You can change the weather and the opposing Pokémon.