To catch a pokemon without fail, throw a great ball or ultra ball at a pokemon. As soon as the pokeball closes NOTE: Exactly when the pokeball closes, as in when it closes and it is still in the air.) Hold down A,B,L and R at the same time. This works all the time for me. If it doesn't, you are doing something wrong. NOTE: Does not work with Regice, Regirock or Registeel.