I have no idea

Someone new

Thought that maybe we see more familiar faces again.

I think we must have Someone who has a Mega or comes from Sinnoh (because that is the Origin region for Mega Pokemon) or Someone who is an Autority in Mega's.

Thought Kalos was the origin of Mega Evolution. You might think of the Hisihu from Pokemon Legends Arceus.

I thought Sinnoh but after a check its indeed Kalos. I think i was indeed confused with the hisihu forms

It would be great to se Alian again because he and Ash will promise to battle each other again someday, plus I'm curious to know if he found his own Keystone and Mega stone and more importantly which of his Pokemon will mega evolved either Charizard, Tyranitar or Metagross?

@Gligorvic I think it is Mega Charizard X like before. How I like for Alain to use different Mega Evolved Pokémon in each match like Mega Tyranitar, Mega Metagross, Mega Gengar, Mega Glaile, Mega Gyarados, and Mega Manectric.