Instructions
Walk around any patch of grass, inside any cave or on any surface of water. After a few moments, you will encounter a wild Pokemon. Please note that you can only catch wild Pokemon. If you try to catch another trainer's Pokemon, you will lose your Pokeball.
Select one of your own Pokemon that is strong against the wild Pokemon that has appeared. An example would be using a Water type Pokemon against a Fire type Pokemon. Not only will this make it easier to damage the wild Pokemon, but your own Pokemon will take less damage from any attacks.
Lower the wild Pokemon's health until it registers in the red. Although you can sometimes capture a wild Pokemon at full health, lowering its health makes it more likely to successfully capture. If you have any moves that induce a status like "Sleep" or "Paralysis," use them. Try to avoid using moves that induce "Poison," "Burn" or "Confusion" as that can lead to the wild Pokemon's defeat. If the Pokemon is defeated, you will be unable to capture it.
Select a Pokeball from your inventory and use it against the wild Pokemon. If the Pokemon breaks free, you will need to use another Pokeball. If a Pokeball shakes three times and the wild Pokemon does not break out, the wild Pokemon has been caught.