Lisa want to use the Train to access The Multiverse.
Knowing who Lisa is, she would likely want to visit other worlds using the Train as a gateway. Goh will allow one of the Star Voyagers to train with Scorbunny.
He's literally the only member of the team with a Pokemon, and he might want to help the members get prepared should he become unavailable. Girl Jordan will eventually become the Trip/Mallow of This story.
What I mean is that eventually there will come a moment when she explains to everybody why Stella most likely disappeared, being a former passenger and all, though hopefully with less Brutal Honesty. The reason Goh and Ash had a fight
- Goh has feelings for Ash, but Ash is either unreceptive to such attractions and Ash gently telling Goh he isn't into him like that hurt, or Goh might have seen Ash with a girl and thus Ash has no idea that he hurt Goh's feelings.
- A rougher take on episode 7 where Goh's funk about his loss to Hodge wasn't cured by Ash using Mimey to prove a point and it continued to mutate.
- Goh felt he had 'dibs' on Gengar and it created a fight.
- Ash did something that was well intentioned but angered Goh, like Ash took to training Goh's team when he was away and Goh took that far worse than Ash expected.
Koharu comes from a world where the events of Boiling Point went horribly wrong
We all know how her history ends, with her getting the Youkai to stop and being forgiven for everything. But what if this Koharu's world feature events where things went even worse, with her family actually damaged and her Youkai "friends" unwilling to listen to her? So instead of being a Karma Houdini regarding sending many questionable creatures into her hometown that cause a lot of damage, she ends up becoming a pariah once those creatures prove themselves untrustworthy and everybody realizes she took them in in the first place.