So who takes the starter that's strong against yours if this ohana chipmunk fuck takes the one weaker to yours?

I mean, it can't be Lillie. Well I take that back, theoretically it could, but I kind of feel like that's not the direction they want to take her in what with the m y s t e r i o u s n e s s and whatnot. They're not good at subtlety. The website beats you over the head with it.

If she had the stronger starter, there was no reason not to show her using it, since they're all already revealed. She wasn't shown battling unlike Hau, so I am willing to bet her team is all Pokemon that are as of now unrevealed, so they can't show it yet.

Consequently, the reason why we haven't seen the stronger starter is because it belongs to a character that is as of now, unrevealed.