Hala's the kahuna of Melemele Island and Hau's grandfather. He's known for his Fighting-type Pokémon and hands out the Melemele stamp when trainers manage to beat him in battle. By the time of Sun and Moon, he's actually made it into the Alola Elite Four.
Before all that, Hala was Professor Kukui's mentor—and Guzma's too. He tried to keep things balanced between the two, but Guzma eventually got frustrated with Hala's approach and decided to pursue strength his own way, ditching the whole Z-Ring and Z-Crystal system entirely. That falling out gets revealed way later in the series.
Content compiled by AnimeList.moe from publicly available sources.
