That depends on what kind of Pokemon you're looking for.
But as for catching a Pokemon, that much is simple; you weaken it by engaging it in a battle, and once it's weak enough you can try to capture it. Status afflicting moves such as Toxic or Thunder Wave make it easier, as well.
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But as for catching a Pokemon, that much is simple; you weaken it by engaging it in a battle, and once it's weak enough you can try to capture it. Status afflicting moves such as Toxic or Thunder Wave make it easier, as well.