From Bulbapedia, the community-driven Pokémon encyclopedia.
(Japanese: マホラ小島 Mahora Islet) is the fourth island Ash, Iris and Cilan visited during their travels through the Decolora Islands. It is only accesible from Mahora Island when the tide is low, since the only bridge connecting the islands is destroyed.
Being mostly a forest, the only building in the island is an abandoned Pokémon Center. Giant Pokémon are said to inhabit here, however, all of them are illusions created by a Zoroark in order to protect the other wild Pokémon from poachers.
Pokémon seen in Mahora Islet