Not entirely sure but the final island's Kahuna's Pokemon are almost level 50. So maybe pretty late, but it's before the endgame I'm pretty sure.
Have some images of story related people (SPOILERS SPOILERS)
http://i.imgur.com/ouzUmxM.png (masked wrestler the royal - think he's some sort of battle royal person)
professor burnet:
http://i.imgur.com/HpaEXuD.png (kukui's wife)
trial captains (bottom 2nd from left is fairy-type captain mina)
http://i.imgur.com/ONu6yT0.png (pretty sure the dude in black is the dark-type kahuna nanu)
anabel:
http://i.imgur.com/imxHXkX.png
grimsley, colress, kahili, sina:
http://i.imgur.com/OnT5vzg.png
working on getting official source for images cause idk where theyre from ^
also the ost:
https://www.youtube.com/playlist?list=PLEkW7MtXullj8h3ADLC1WfMmqUupZVHOY (op should prob be updated)