Akuma

Akuma, known as Gouki (豪鬼) in Japan, is a character from the Street Fighter series. He is a cold and extremely powerful warrior whose sole purpose of existence is to hone his fighting skills by battling and destroying strong foes. He rarely displays any sign of emotions, aside from occasional bursts of anger. He is Gouken's younger brother and Ryu's adoptive uncle.

Street Fighter X Mega Man
Akuma appears in Street Fighter X Mega Man as a secret final boss. His weakness is the Hadoken.

Attacks

 * Gou Hadouken (a purple version of it)
 * Shakunetsu Hadoken (a fire version of the Hadoken)
 * Zankuu Hadoken (an airborn version)
 * Tatsumaki Zankuukyaku (a stronger version of Ryu's Tatsumaki)
 * Tenmakuujinkyaku (a downward kick)
 * Messatsu Gou Shourryu
 * Misogi (an area of effect attack)
 * Shin Shun Goku Satsu (an instant death move)

Strategy
As the true final boss, Akuma is the strongest enemy in the game. Like in his boss incarnations in Street Fighter, he fights as a more powerful version of Ryu. Akuma attacks with the Gou Hadouken, though less frequently than his other attacks. The airborn Zankuu Hadouken is his most used projectile, where he jumps and fires two downward Gou Hadoukens. He tends to follow this up the Shakunetsu Hadouken, which is faster and much more damaging than the standard Gou Hadouken, and also travels through Megaman's projectiles. His Shoryuken and Tatsumaki are both stronger versions of Ryu's, though the former doesn't pose much danger since it can only hit Megaman when he's near him. The latter needs to be jumped over while Akuma rushes towards Mega Man. Akuma also uses a downward kick while jumping, and a Misogi that has him jump off screen and then come back down and releasing the shock wave. His special is the lethal Shin Shun Goku Satsu, which has him move at a great speed across the room and kills Mega Man instantly, should he ever succeed in coming into physical contact with him.

Akuma usually opens up the fight with the Shin Shun Goku Satsu, so be sure to jump over him when he does. He usually will stay on side of the screen and either jump and fires his Zankuu Hadouken, or stays on the ground and fires Gou Hadoukens, before firing the Shakunetsu Hadouken. When moving across the screen, he will alternate by moving using his jump kick or preform two Tatsumakis followed by a Shoryuken, or use Ashura Senku, which causes him to travel much faster. Whenever Akuma builds up his Super Combo Gauge again, he'll use the Shin Shun Goku Satsu.

It is worth pointing out that the usage of E-Tanks during this fight are useless since, while Mega Man recovers health, Akuma will regain his health as well.

Unlock Requirements

 * To fight against him, Mega Man must obtain a Perfect victory (Landing the final hit at Full Health, meaning that a last second E-Tank usage will also result in a Perfect) against four or more stage bosses and beat the game without the use of continues.
 * Boss Rush Perfects count towards the other Secret Boss.

Trivia

 * If one is to get a game over against Akuma, they will still spawn in the screen which Megaman drops down before fighting Akuma.