Fairy/cute theme for mine. Those not in the know probably expect him to use dragons or dark types or pseudos or something based on the way he looks/acts, and then get completely caught off guard when a Belly Drummin' Azumarill wrecks their life.

As for the rest of the team, he's at least got a Dedenne that basically lives atop his head and a spoiled-rotten Alolan Ninetales. Not sure about the rest. 

For the amount of people, could also have Champion, Elite Four and one or two Gym Leaders only (the highest ranking ones), maybe? Perhaps they're good enough to be on the running for Elite Four in the future, and that's why they know the rest. Mm, though it makes for a less cohesive group than just having the 4 + Champ. I'm fine with whatever, but all 8 Gym Leaders might be a bit too many people.