So I saw serebiis page on Helioptile's evolution and they have its Dream World Ability listed. So, is the Dream World open, or can you get Pokemon with their DW ability ingame like in BW2?
The dream world has already been opened. It was opened at the start of October as a trial. Now the trial is over and the dream world is open for anybody. The dream world for Pokemon B/W and B2/W2 will be closed in December.