Things You'll Need
Instructions
Engage the rare Pokemon with a Pokemon that has an opposite attribute. For example, if you are fighting an ice Pokemon like Regice, you will want to start the battle with a rock-and-steel type like Steelix.
Use any combination of attacks that are strong against the rare Pokemon's element and use healing items or skills when necessary. Continue this step until the opposing Pokemon's hit points are very low.
Apply negative status conditions that immobilize the opposing Pokemon. These could be attacks that induce sleep from hypnosis, paralysis from the stun spore, or freezing from the ice beam. Switch around the battle team if necessary to use these attack types.
Throw Ultraballs at the weakened and status-afflicted rare Pokemon. Repeat step three when the negative conditions wear off, then step four until it is caught.