According to Serebii and the new opening, Serebii seems to thinks Ash gets Noibat and Serena gets Eevee. (Didn't notice someone had said this yet)
I haven't seen it yet, so I can't say much. Serebii also says that Noibat seems to have trouble flying. I really don't mind at all. I never even liked Goomy line until the anime. I wanted wanted Ash to catch Noibat as he has never caught a bat type, but I wonder if it will evolve sense Alexa has a Noivern?
And honestly, I don't mind him getting so many flying types. Flying types is one of my favorite types. Still leaves him with 1 spot and if he gets other pokemon past his 6 on a team or not.
But so far, his team has been pretty unpredictable this season. So I am not sure what he will get. I still hope for snover, phantump, or honedge. However, if he catched a Bergmite, it might make me like that pokemon more like it did with glalie and goomy.
As for Serena, I would love for her to catch something like Dawn did with Mamoswine. But I would also like Serena to continue to follow the trend of her getting a pokemon like Ash has in the past when it comes to game females. So maybe a Snorunt, but evolve into a Froslass.