>>58227252Ash would probably be somewhat like Alder, a traveling champion who solves problems where he goes and tries to help humans and pokemon connect with one another. And similarly to Alder I can see Ash struggling to pass the torch to someone else.
So a story about an aged Ash encountering a young trainer and, by the end of the movie, passing the torch onto them could work well. Just as Alder passed his torch to Iris.
If you mean something like a young adult Ash (like Leon aged) then I suppose something like the Rainbow Rocket plot crashing the PWC Finals and the involvement of Mewtwo could work. I wouldn’t say Ash catches Mewtwo but seeing them work together to stop Giovanni once and for all could be interesting.