The Pocket Dimension is a blank dimension filled with nothingness. In order to get there build a nether portal but instead use iron blocks. There are two types of this dimension, normal and corrupted when Herobrine's head is attached anywhere on the portal.
There is no use of the dimension except when it is corrupted which can allow you to summon the 2 bosses, Steve and Nega Steve.
Unfortunately, this article is a bit void of content. It should be bursting at the seams!This is a community fanon, just dive in and add anything you can think of. Be nice.