How to get Legendary Island
Beat the game (by defeating Rayquaza) and then go to battle Zapdos, Moltres or Articuno. Then when yo battle them they will ask you to enter in your rescue team. Then you have the Legendary friend area I wish. Good luck it only took me 6 minutes Zapdos lv 40 and Moltres lv 43, Articuno lv 45.