That depends on who you ask. While some people train Pokémon as a hobby, for others it's a full-time job. We compete in battles - contests of skill and strategy that test the strength of the bonds we foster with our teams.

[ his eyes fall to metagross, smiling at it fondly before turning back to tadashi. ]

If battling competitively is your calling, you can choose to travel the world and take on the Pokémon League challenge - an organization of various strong trainers specializing in a particular style of battle. Should a Trainer surpass the eight certified Gyms and their Leaders in their region and succeed in taking on the endurance challenge of the Elite Four, their final goal is to defeat the Champion and inherit their place among the strongest Trainers in the world.
[ phew. that sure was the base structure of every main series pokémon game abridged, but he doesn't mind explaining. in fact, he finds himself chuckling at his last words. ]

Though a goal like that can only achieved by a select, dedicated few. It's quite the responsibility.