Ep. 40: Balloons, Brionne, and Belligerence!
Lana and Popplio have been practicing the Z-move Hydro Vortex, but so far with no success, and Lana is feeling discouraged. Ash, Lana, and Mallow meet a performing Brionne and its trainer Ida who possesses a Z-ring with a Waterium Z-crystal and can perform Hydro Vortex. Lana begs Ida to teach her. Ida and Brionne are helping her boyfriend, Kanoa, to search for a mysterious Mystic Water that may be located in the wreck of a sunken ship, and Ash, Lana, Mallow and their Pokémon join in to help. When Team Rocket try to steal the Mystic Water, they anger a Dhelmise that's been living on the wreck and trick it into attacking Kanoa's boat. When Brionne is knocked out and Dhelmise creates a deadly whirlpool, Lana and Popplio are able to use Hydro Vortex to defeat Dhelmise. With everyone safe, Kanoa finds the Mystic Water and gives it to Ida. (Source: Wikipedia)