One of the trailers shows Guzma with a lvl32 ariados on Ula Ula island, the last trailer shows the beginning of alola league, also the place where the workers say they are buolding it is right before the icy mountain, which name means victory in hawaiian.
The island challenge is just the first part of the game, after you complete it and stop the tomfuckery of team skull, gyms shall be built on those empty spots in every city, and Aether shall show their true face, Yaboi and the Yaboiz help you so Guzma becomes the 8th gym leader, the kahunas are the elite four and the champion is Kukui, he has plenty of battle intros.