From writing standpoints I'm intrigued to see how he would cook a April or Ashelin story, since they simply dont have much room to work with as a mc.
Safe bet would be Lara Croft or Cornelia trainer with the 2 as side.
Idk, what would that even be?
April, Ashelin, and Lara already have trainer arcs in SC34 - the latter twos is even connected with a romantic subplot. So would he just do that again? Probably not, even if he reused the alternative dimension thingy.
I could see him have the Old Man accompany Ashelin to her homeplanet, where he advises her on what to do within the ongoing war - kinda like he advised Jasmin in QT; this would probably trigger a bunch of people though
. As for Lara and April I don't even see such an "obvious" setup, where he couldn't just do a character focused Season 2 episode instead.
Lastly his take on Cornelia kinda concluded in QT - yet, I know nothing about the W*I*T*C*H franchise, but there's surely stuff he hasn't implemented, that would make for a satisfying trainer setup.