Carvanha's best moveset in Pokémon GO is Bite and Crunch, with 11.71 damage per second, and it can deal 62.7 damage before Carvanha faints. This is true when battling in neutral weather.
All Carvanha movesets ranked
Here is a complete list of Carvanha movesets in Pokémon GO, ranked by their DPS and TDO. You can change the weather and the opposing Pokémon.