This sound is from Gyarados Soundboard

Gyarados (Gyaradosu) is a Pokémon species in Nintendo and Game Freak's Pokémon franchise. Known as the Atrocious Pokémon, it is the evolved form of Magikarp, well known for its fierce temper and reputation for causing nothing but destruction.
See also: Magikarp, List of generation I Pokémon, Pokémon: The First Movie, Unshō Ishizuka, Misty (Pokémon), and Pokémon Ultimate Journeys: The Series.