Baton Pass will pass along any stat changes the user has onto the next Pokémon, making it a useful tool for setting up a sweeper Pokémon that cannot set up on its own. It also passes along Substitute, meaning the next Pokémon gets a free meat shield at no cost of their own. There is also a strategy known as Wish passing, where a bulky Pokémon like Vaporeon uses Wish, then uses Baton Pass to switch to a teammate in need of healing.
Some Pokémon that can use Baton Pass effectively are Blaziken and Scolipede, to pass along Speed Boost, Smeargle to pass along Geomancy (or any boosting move really), and if you want to be a little crazy, Eevee can pass along Extreme Evoboost.
I'm sure you can find other ways to utilize Baton Pass, but that's the gist of it.