Hydro Cannon is a slightly inaccurate but very highly-damaging Water-type move introduced in Generation III. For all intents and purposes, it is a Water-type Hyper Beam.

Learnset

Generation III

In FireRed and LeafGreen, an elderly woman on Cape Brink will teach Blastoise, Feraligatr, or Swampert Hydro Cannon. Like Frenzy Plant and Blast Burn, the Pokémon must have a very high happiness rating.

Another way to get the move would be to clear the Mt. Battle challenge in Pokémon XD: Gale of Darkness, then choose Totodile as the prize.

Generation IV

An elderly man, much like the woman on Cape Brink, appears on Route 228 in the Battle Zone, and will teach it to the three Pokémon that could learn it in Generation III, as well as Empoleon. He will also require that the Pokémon that is to learn the move has a high happiness rating.

In other languages

French: hydroblast, German: aquahaubitze, Italian: idrocannone, Spanish: Hidrocañón.

Template:Project MoveDex notice

Variations of the move Hyper Beam
Giga Impact • Rock Wrecker Hyper Beam • Blast Burn • Hydro Cannon • Frenzy Plant • Roar of Time