To catch zapdos you will need a pokemon that knows self destruct and is at level 50, a pokemon that knows hypnosis, and several ultra balls. So first send out the level 50 pokemon that knows self destruct. Use self destruct and it will deplete all of zapdos' hp except 1. Then send out your pokemon that knows hypnosis. Use hypnosis on zapdos. While it is asleep, use your ultra ball and hold b when the ultra ball opens. It will catch zapdos without fail.