Call me crazy, but… Serena got excited over an Umbreon design, and it just so happens that Eevee’s scene in the OP shows it performing in the moonlight. Sure, this could mean nothing, but what if…?
I know Eevee is like 99% sure to evolve into Sylveon, but now I think maybe there’s that super unlikely 1% chance it’ll end up as an Umbreon.
(bonus: if they want her Pancham to evolve, she’ll have to get a dark type first if they’ll stick to the game rules)