Details: One of the ten possible challengers you will face as you sit on the
Champion's Chair in the Champion's Hall after defeating the Elite Four is Professor
Kukui. He doesn't have any desire to become champion for the Pokemon League he built, but despite this, he still feels he can be a challenger. He still doesn't specialize in any given Pokemon Type, having the same team as you faced at the end of the original Pokemon League. His Starter Pokemon is still super effective to yours, and he is the strongest challenger you'll face.
Challenger Kukui (Rowlet Starter) - Level 65 Lycanroc, Level 65 Ninetales, Level 65 Braviary, Level 65 Magnezone, Level 65 Snorlax, Level 65 Incineroar w/
Firium Z
Challenger Kukui (Litten Starter) - Level 65 Lycanroc, Level 65 Ninetales, Level 65 Braviary, Level 65 Magnezone, Level 65 Snorlax, Level 65 Primarina w/
Waterium Z
Challenger Kukui (Popplio Starter) - Level 65 Lycanroc, Level 65 Ninetales, Level 65 Braviary, Level 65 Magnezone, Level 65 Snorlax, Level 65 Decidueye w/
Grassium Z