You get 'em for challenging the leader at a Pokémon Gym and winning. [He grabs his bag and drags it over closer, rummaging through it. Eventually he pulls out his badge case and flicks it open. There's only a single badge in there, the Zephyr Badge from Violet City.]

Gym Leaders are strong trainers who usually specialize in a certain type. [At the very least, Ryuuji isn't opposed to explaining things as needed.]