In Pokémon Sun/Moon, since you're the first Pokémon League champion, you're set to defend your title as Pokémon League Champion, rather than repeatedly taking the title from your rival or whoever the champion before you was. Unlike previous iterations in the series, who you fight in the championship match changes.
So far, after beating
Professor Kukui,
I've had to defend my title against
Hau and Molayne.
This leads me to believe that there are a vast number of challengers I could have to defend my title against. However, at least one captain is also a member of the Elite Four, so not all captains could be challengers. That said, is there a list of who all could potentially challenge me? I know Red and Blue are in this game, so could they challenge me?
Best Answer
Serebii has compiled a challenger list. They state that there are 10 potential challengers you will face, chosen at random. This is excluding the first time you beat the league which is fixed. According to Bulbapedia, the first title defense (second time in the league) is also a fixed challenger. And one challenger only appears on a certain day of the month.
Challenger names listed in spoiler below.