Isle Avue is an island that acts as a Hot Spring with two given effects: for Pokemon, it will increase their level of happiness with you; for Pokemon Eggs, it will cause them to warm up even more and eventually hatch. Poke Beans will double the increase in happiness and cause Eggs to hatch faster. Your Pokemon's Happiness, like with the Happiness Checker, can be discovered through given statements. If you keep your Pokemon in the Springs for more than twenty-four hours, their Happiness will actually begin to drop.
The first rank for this island is unlocked with 60 Pokemon in your Boxes and 60 Poke Beans, with a limit of 6 Pokemon. The second rank comes with 75 Pokemon in your Boxes and 150 Poke Beans, with a new limit of 12 Pokemon. The final rank can be seen with having 90 Pokemon in your Boxes and 240 Poke Beans, having a grand maximum of 18 Pokemon at any given time.