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By a device known as a "PokéBall" at them.
There are many variations of PokéBalls such as the "Timer Ball" and "Luxury Ball".
Like Pokémon, they have unique abilities.
For example:
>Timer Ball
The longer a battle with a Pokémon, the higher the chance of capture.
>Luxury Ball
Pokémon caught in this contraption will grow friendlier to their trainer faster.