The "enters" effect moves all Equipment onto the Battlemaster, regardless of whether that Equipment was attached to other creatures.

Other players' Equipment is moved onto the Battlemaster as well as your own. This doesn't change who controls the Equipment or who can activate its equip ability to move it onto another creature.

If an Equipment can't equip Vulshok Battlemaster, it isn't attached to the Battlemaster, and it doesn't become unattached (if it's attached to a creature).