Chien-Pao's best moveset in Pokémon GO is Splash and Struggle, with 13.33 damage per second, and it can deal 345.1 damage before Chien-Pao faints. This is true when battling in neutral weather.
All Chien-Pao movesets ranked
Here is a complete list of Chien-Pao movesets in Pokémon GO, ranked by their DPS and TDO. You can change the weather and the opposing Pokémon.