Some people are more interested in the fashion of the Pokémon games than anything else, and those people include this writer. The characters seem to be largely dressed in school outfits, but their hats, hairstyles, bags, and glasses change. Also sometimes they wear shorts, and sometimes they wear trousers.
So, there will probably be an element of fashion, like in Sword & Shield... but we're intrigued about how it'll interact with the uniforms.