Game:Monstro

Monstro is a boss exclusive to Kingdom Hearts Birth by Sleep Final Mix. It is fought within the Monster of the Deep battle. The battle is be made up of a timed stage where the player can attack Monstro directly, and an acid-filled stage within Monstro's belly where the player is sent once the three minutes run out. The player must defeat the Unversed within Monstro to escape and try to damage Monstro further.

Strategy
Monstro is a unique Mirage Arena boss. The battle begins in a stage within Monstro's belly where the player must defeat the Unversed within Monstro to escape. Once all the Unversed are defeated, the true battle begins as Monstro spits the player out.

Monstro is a tough opponent in battle as he has high HP, and compounding the difficulty is the fact that the player is only given three minutes to damage him as much as possible and the arena consists of small islands. In terms of offense, Monstro will slam the water to create large, damaging tidal waves. the boss will also body slam the island the player is on to cause large damage, as well as slam his tail down on the player. Monstro will charge directly at the player to knock him or her off the island. And lastly, the boss will attempt to inhale players in, and if successful, spit them out via the blowhole, causing damage. The player can stop this attack by throwing an explosive barrel at him, knocking him out. At this time, the player can cause the most damage to Monstro. To damage Monstro, the player can throw the explosive barrels at him when he rises above water, and should use distance attacks such as Shotlocks, and fire commands. After three minutes of combat, Monstro will swallow the player, where he or she must defeat the Unversed to escape and damage him further. However, the arena is now filled with acid, which can damage players. By repeating the above strategy, Monstro will eventually fall.

Development
Interestingly, Monstro was not the original choice for an additional Disney Boss for Kingdom Hearts: Birth by Sleep Final Mix. A Square executive originally suggested having one of the Titans appear, but as they'd already included the Ice Colossus, they opted for an alternate boss similar in size, resulting in Monstro appearing instead.