Obviously, Ash's goal is the defeat Leon. But i don't think its ever mentioned he wants to beat Leon to win the PWC.
I just can't see Leon staying the PWC champion title the moment gen 9 is revealed/announced, but its then that Leon will be old news the moment gen 9 is released and in the PWC format as such they need to make the gen 9 champion an ever bigger threat than Leon was.
As such, i can see it as more of a possibility Ash defeating Leon in a PWC match that isn't for the title, because Leon previously lost to the gen 9 Champion, than Ash defeating Leon for said title and then losing the title to the gen 9 title right away (Making his title win against Leon pointless). Especially since this will generate a bigger outcry than Ash losing to Alain in the Kalos league or Ash defeating Leon when its not for the title.
What is your take on it.