Water Spout (Japanese: しおふき Whale Spout) is a damage-dealing Water-type move introduced in Generation III. It is a variation of Eruption and can be considered the inverse of Reversal and Flail.
Water Spout does damage proportionately based on the user's HP. This move's base power reduces as the user's HP reduces and is calculated by the formula:
Hence, at maximum power (100% HP), the move's base power would be 150.
In a Double Battle, Water Spout will hit both opponents. In a Triple Battle, Water Spout will only hit opposing adjacent Pokémon.