From Bulbapedia, the community-driven Pokémon encyclopedia.
Wales Island (Japanese: ウェルズ島 Wells Island) is an anime-exclusive location in Hoenn, featured in Where's Armaldo?. It is a crescent-shaped island located somewhere between Mossdeep City and Sootopolis City.
There is a town located on one side of the island, while the rest of the island is uninhabited by humans and considered to be a nature preserve. Professor Proctor and his wife Annie live on the island and also run a Fossil laboratory there, where they have resurrected several ancient Pokémon. Initially, the Professor hoped to invite people from all around the world to the island so they could see the Pokémon. However, after an Armaldo went on a rampage, the couple decided to abandon these plans. They instead promised Ash and his friends that they would keep the island a secret and work hard to make sure the Pokémon would be safe.
According to Brock's handbook, Wales Island has remained unchanged for 1,000 years, and ancient Berry trees continue to grow on one of Wales Island's capes. Professor Proctor showed Ash and his friends a simulation of the island's history, which explained that the island was once part of the mainland thousands of years ago, but rising waters led to its geographical isolation. Wales Island remained home to Anorith, Lileep, and their evolved forms Armaldo and Cradily, but they became extinct more recently.
Pokémon seen on Wales Island