From Bulbapedia, the community-driven Pokémon encyclopedia.
An unnamed island in the Orange Archipelago appears in A Way Off Day Off. It is probably the deserted island located between Murcott Island and Mandarin Island South shown on the map that came with the DVD pack.
This island is uninhabited, and is home to many different fruit trees. Many Farfetch'd live on this island, and it is hinted that they migrate here once a year.
Pokémon seen on the island