>>30469854you'll receive/ have a key item called a Zygarde cube on the second island. Once you have it, you'll be able to pick up 100 Zygarde cells scattered throughout the 4 islands and the artificial one. 10 will give you a 10% form Zygarde, 50 a 50%, and 100 will change your ability so that when your health reaches half, Zygarde changes into 100% form in battle.
