You must have two DS systems(Or at least access to two) of any kind(they do not have to be the same kind eg. DS lite and DSi will work together). Also have a Gen IV game. You must TM Dark-pulse to a male Gyrados, Arbok, Ekans, or Seviper. Then transfer it to B/W with the Poketransfer. Then you must have a female Hydregion(or any of its evolutionary forms) then put them both in the day care and the offspring will be a Deino with Dark-pulse.