If it's for cartridge, you can use also use sample teams by going into Battle Stadium (VS in the main menu) and going for spin with that to learn what's common and whatnot. You can also build your own team and ladder with it for a while to see what your team is weak vs and if they are any deadweight members you can replace; an example is find a Pokemon you really want to use and build around it by covering its weaknesses and whatnot. Simple things such as learning the type matchups, changing your battle style from Switch to Set, and even spectating high level players can add up as well.