To do this you must have a torterra or empoleon below level 60. when the classical music plays, shut your ds. then you must only use the starter. use the move it's known the longest until it's hp is in high yellow. then hold L and R and use second most powerful move. dialga should have 1 hp or so left. if it doesn't immeadeatly throw an ultra ball. if it is, it is safe to throw the pokeball, but you could use an ultra ball just to be safe, because if it breaks out, good luck catching it.