OK, I'm going to assume you mean the password to Team Plasma's ship (Plasma Frigate) in B/W 2. I don't recall any other 'barrier' in the game other than that. To save some time battling the Team Plasma Grunts, the password is 2202, however you need a Plasma Card to enter the password, which can be obtained by defeating one of the Plasma Grunts under the pipe puzzle. Once the password has been gained, all the beams will disappear. When you proceed, Zinziloin will battle you, and later Colress as well.