Ash and company come to a place called Porta Vista, which is being attacked by
Tentacool. On the way, they are warned of this fact by a friendly Horsea, and
save a ship full of people who were attacked. On the shore, an old bag, Nastina,
offers them a reward for getting rid of the Tentacool. They are damaging the
opportunity for her to set up the sea-side hotel she wants to.
Team Rocket steps in first, and dump stun sauce in the water to paralyse the
Tentacool, so they can steal them all, and voila, everyone's happy. However, it
doesn't work. The stun sauce ends up angering a Tentacool and causing it a
mutant evolution, into a GIANT Tentacruel. Tentacruel uses Meowth to speak, and
tells the people that it will destroy their world as they destroyed its - the
sea. But Misty manages to pacify it, promising that from now on, humans and sea
creatures will respect each other's worlds. Then Misty gets the Horsea from
before as her own Pokémon.