Vanitas' Lingering Spirit

Vanitas Remnant makes its only and first appearance as an optional boss in the after game of Kingdom Hearts Birth by Sleep as a secret boss.

these are ways for each character to beat him.

Aqua: At the start of the battle, he will encase himself in a dark orb, creating shadow replicas of him. Cartwheel or use a shotlock to be immune to this attack. It might be good to use seeker mines, as that does a great amount of damage. It is also good if you are level 40 or over for it. When his health goes below halfway, he will start chaining combos to do even more damage. Keep doing a mine lay and run fight, and the Vanitas Remnant will eventually fall. As a reward, in english you get the Void gear, japanese you get a secret gem.