Rather than having Gyms in the Alola Region, when children become 11 years old, then they have the ability to go through the region and participate in special Island Trials. These trials are led by Trial Captains, who you don't battle at the time, who give specific tasks and then typically end with a battle against Totem Pokémon, which are larger variants of the Pokémon that have their stats boosted by an aura. There are 7 trials across the Alola Region

Trial #1: Normalium Z

Trial Captain: Ilmia
Location: Verdant Cavern - Melemele Island

Details:
The first trial is set by Ilima. When you enter Verdant Cavern, you are sent to find the three Pokémon that are in the cave. These Pokémon are Yungoos (Sun) or Rattata (Moon). When found, they will attack you, at Level 11, and cannot be captured. Half way through the trial, Team Skull appear to mess things up.
Totem #1: Gumshoos/Raticate

Trial Captain: Ilmia
Location: Verdant Cavern - Melemele Island

Details:
Due to his position as Kahuna of Melemele Island, Hala, was invited by Kukui to become one of the Elite Four. He focuses on Fighting-type Pokémon.