Most competitive Pokémon players spend anywhere from a few hours to weeks building, refining and practicing with a Pokémon team before bringing it to a live event. However, as it turns out, constant preparation and practice aren’t of central importance in competitive Pokémon. Some players understand the game so well that they can outplay their opponents with a team that was literally just handed to them. To learn more about this strategy, click here.
Source: Compete Kotaku