Tentacool & Tentacruel

Pokemon: Still in Porta Vista, Ash, Misty, and Brock must wait for another boat to take them to their next destination. After witnessing a boat explosion, they use their pokemon to save the crew. They are thanked by the boat's owner, Nastina, who then asks them to exterminate all of the Tentacool who are harming the construction of her new underwater hotel. Misty refuses saying Nastina is doing all the harm and brags Ash and Brock out of there. Team Rocket then takes up Nastina's offer and once again they ultimately fail, and in the process cause a Tentacruel to grow to a enormous size. The water pokemon then invade the city with the goal of destroying all the humans, and it is up to Ash, Misty, Brock, and their new Horsea friend to save the residents.