Game:Vanitas

Vanitas appears as a boss in all three storylines in Kingdom Hearts Birth by Sleep. In Terra's storyline, he only fights Vanitas once along with Master Xehanort at the Keyblade Graveyard near the end of the story, but the battle stops halfway. In Ventus's storyline, he fights Vanitas three times in the game: Two out of three of the fights are fought at the Keyblade Graveyard, with the first with the assistance of Mickey Mouse, the second fight being the pentuiltimate fight of the story, and the third fight being the final boss where Ventus fights Vanitas (with an incomplete X-Blade) in their Awakening. In Aqua's storyline, she fights Vanitas three times in the game: the first fight in Radiant Garden, the second fight in Neverland, and the last fight alongside Mickey Mouse in the Keyblade Graveyard, where Possesed Ventus

Terra
Terra will fight both Master Xehanort and Vanitas two on one. Vanitas should be the primary target as Xehanort will mostly dodge and keep away from Terra. Vanitas will use his fire ball, lightning, Command Style, and regular physical attack here, as well as his typical shadow counter. However he isn't very difficult as after sustaining minor damage Vanitas will flee, leaving Terra to face Xehanort alone. If you wish to speed things along casting Magnet will stun Vanitas, putting him at Terra's mercy. But this is merely a warm up for Terra, and isn't difficult at all.

First Battle
In Aqua's first battle Vanitas will go easy on her. He'll physically attack, launch a fireball that breaks into smaller fireballs, and leap into the air and rain lighting bolts. Vanitas also has an ability where after being hit a certain number of times he'll warp above Aqua leaving a shadow where he used to be, and does a leaping slash from above. Therefore getting off a full combo or Shoot Lock is difficult. If you wish to play it safe you can simply guard all his attacks and counter which will damage him without him being able to counter, or you can tough it out and trade blows with him doing your best to avoid his counters. A weakness than can be exploited is that Vanitas can be affected by Magnet spells. Casting one on him will trap him in the air where he can attacked without fear of countering, and will also leave him stunned for a few moments after this, again allowing him to be attacked without the ability to counter.

Second Battle
Vanitas is no longer playing around with Aqua so he's more aggressive this round. In addition to his other moves that he'll carry over he has a new Command Style like move where he glows red, dives under ground and homes in on Aqua before attacking directly under her. This can be avoided by letting him track you and then quickly Wheel Rolling away from the attack. However he'll still be glowing for awhile after this and while he is Vanitas will add another hit to his usual Keyblade combo that throws out a cresent wave of energy that does additional damage and can hit Aqua from long range. He has more health too but beyond this is basically the same as the first battle. Guard and counter to play it safe or stun him with Magnet like before.

Third Battle
During the third battle, Vanitas will possessing Ventus from the inside and wields the Completed X-Blade. Mickey will assist Aqua during the battle. Vanitas's battle style is almost the same as the previous battles, albeit having new attacks and variations of his previous ones. Vanitas utilizes the same two hit combo and releases a crescent wave of energy, though it will stay out for a longer period of time. Also, Vanitas will dive back into the ground after diving upward from the ground and repeat the process two more times, making the move harder to avoid. A new skill Vanitas utilizes is a thrusting move similar to Sonic Blade though he will zigzag around instead of constantly thrusting, which should be avoided by leaping around. If Vanitas is hit a certain amount of times, he will leave behind a shadow where he used to be and leaps above Aqua and performs a leaping slash from above creating large crstals through impact. This attack is more difficult to avoid since it now has a wider range. Another new technique that Vanitas utilizes is when he teleports to the middle of the battlefield and lands a hard blow on the ground creating four shockwaves, this move should be avoided by performing a Shoot Lock or utilizing Holy Burst with Mickey.

First Battle
Vanitas has the same moveset and stats that he did with his first encounter with Aqua, but after he hits you enough times the battle will end and Mickey will join in for a second round.

In the second round you have Mickey as an ally, which allows you to use reaction commands to shield the both of you from Vanitas's attacks and when Mickey prompts you to, go back to back with Mickey and unleash a Holy Burst attack where Mickey and Ventus spiral around firing light energy at Vanitas. This will cause decent damage to Vanitas, but the down side is that Mickey can also cause Vanitas to shadow counter but Vanitas will always appear above Ventus and attack him during this no matter how far away Ventus has gotten him. Unlike Aqua, Ventus will not have the ability to counter after guarding at this point so Magnet is the only way to get off consistant damage without fear of him countering.

Second Battle
Vanitas will open the battle by jumping onto a cloud of Keyblades and riding around the battle area pelting Ventus with ice blasts. He's very hard to hit while doing this but hitting him with a Thunder spell or Magnet spell will knock him to the ground and stun him ending the attack. Otherwise Ventus can just Dodge Roll away until Vanitas stops on his own. After riding the blades Vanitas will immediately do his Command Style attack where he homes in on Ventus under ground. Again avoid this by letting him reach you and then immediate dodge roll away from him. After this Vanitas will go into his usual repitoire of fire thunder and physical attacks for a time before calling the Keyblade cloud and starting the pattern again. Magnet stuns him as always and Ventus will have his own counter attack at this point so you can fight him like you would when using Aqua. The only thing to watch out for that Ventus can only block from in front of him unlike Aqua's 360 degree Reflect, while Vanitas always does his shadow counter from behind so dodge rolling is the only way to avoid damage from it.

Third Battle
Vanitas battles Ven in their Awakening. He now wields the incomplete X-Blade and gets much harder. He retains most of his moves along with variations and tactics. Among these variations are the color of his crescent waves of energy, which are now yellow-orange. Also, when he is struck a certain amount of times, he will leave behind a shadow of himself, but instead of a downward slash, Vanitas will initiate a spinning slash. Vanitas will also disappear and appear in front of Ventus, airborne and initiate a series of slashes. There are three new moves in his moveset. The first is when he charges up the X-Blade to attack, which he uses very often. The charge up will cause fire being shot into the air, then Vanitas will perform a long-ranged slash, strike the ground to from an X shaped shockwave, perform another long-ranged slash and finally leap and fire an X-shaped wave. This is a set of very dangerous moves. However, if he gets attacked while using this, the combo will be interuppted. The second is when he will be shooting across the Awakening with the X-Blade held in front of him, which cannot be blocked. The best way is to just Dodge Roll away. The third is a definite movement and Vanitas will utilize it when he is reduced to 1 HP. Vanitas will rise up charge up in darkness and strike the Awakening, breaking it into fragments. It should be noticed that you take no damage, note that you should heal before this happens, because you won't get another chance to. Here, you will be using the Vanitas Dimension Link. This will allow you to use some of Vanitas's moves and changes your Shoot Lock to his. Vanitas won't be defeated by attacking him, instead, the player has charge the Command Gauge. The Command Gauge can be charged up by hitting him. Vanitas will only be able to perform teleport in front of Ventus and perform a series of slashes, shoot across the battlefield with the X-Blade held in front of him and his Shoot Lock: firing a large blue beam straight at Ventus. There will be incidents whereby the two collide. If that happens, follow the instruction on what to do and keep doing it until Vanitas falls back. This will fill the Command Gauge faster. When the Command Gauge is full, a special command will appear and activate it to defeat Vanitas.