Pokémon: Island of the Giant Pokémon

As our heroes and Team Rocket beat the odds by surviving the sinking ship, they are dragged into another potentially deadly situation when they are attacked by the ferocious Pokémon, Gyarados. One Gyarados becomes many and Ash, friends and foe are swept up in a tornado landing them in various locations on an island. Ash loses Pikachu and the Poké Balls containing Charmander, Squirtle and Bulbasaur. Jessie and James from Team Rocket, who land in another remote part of the island, also lose their Pokémon. Thus both Pokémon and their masters are left searching for each other on this strange island, inhabited by gigantic Pokémon. Where could this island be?