In Pokémon Pokopia, Squirtle’s Water Gun move is used to hydrate dried-up plants. Ditto can learn and use moves from befriended Pokémon, turning familiar battle abilities into practical tools for restoring the environment.
Water Gun complements other environmental abilities. For example, Bulbasaur’s Leafage can add greenery, while different Pokémon provide movement, construction, or terrain-changing functions. These moves are central to Pokopia’s rebuilding loop rather than being limited to combat.
Bubble, Rain Dance, and Aqua Jet are all water-related Pokémon moves, but they are not the specific move identified for watering plants in the game’s introductory descriptions. Squirtle’s association with Water Gun is therefore the precise answer.