How to get Gladion to appear at the Pokémon League in USUM?

Question

I have heard a lot of conflicting information about when he shows up. The general consensus is that he is somewhat rare, but there is some discrepancy as to how and when he appears. Some say you have to wait a month after defeating Necrozma, others say you have to beat Lusamine first, and still others say he is just exceptionally rare. Is there a confirmed method to get him to show up?

Answer 1

The challenger you will face after defeating the Elite Four the second time and after is chosen at random. You cannot really do anything to make him appear, you will just have two cross your fingers I guess. Hope I cleared this up.

Comments

You do have to wait a month after Necrozma, but he is rare.
Source: https://www.serebii.net/ultrasunultramoon/elitefour.shtml