Bijū Dama

Bijū Dama was Kyūbi Naruto's side special move in Super Smash Flash 2.

Overview
When performed, Kyūbi Naruto transforms into his four-tailed form, creates a dark sphere out of Chakra, swallows it, and fires it as a projectile in the shape of a beam through his mouth. The beam fired travels a long distance before disappearing and deals 35% damage with moderate knockback to opponents hit. The beam also has transcendent priority, but it can be reflected. Kyūbi Naruto also fires a separate, short-ranged blast of Chakra as well, which deals 8% damage and extremely high forward knockback to opponents hit, though this knockback is often cancelled by that of the beam.

The move has very high startup lag, leaving Kyūbi Naruto vulnerable to attacks the entire time he is in his four-tailed form. However, it also has strong knockback resistance, allowing him to fire the beam even when attacked.

Origin
In the  franchise, the Bijū Dama is the ultimate attack of a Tailed Beast and, thus, the ultimate attack of its Jinchūriki. To form the attack, the Jinchūriki must gather both Positive Black Chakra and Negative White Chakra  from its Tailed Beast, shape it into a sphere, and then compress it inside their mouth. When Naruto first entered four-tailed, without any knowledge about black or white chakra, he used his skin and blood to do the move, causing them to be burned out by the red chakra.

According to Killer Bee, the Eight-Tailed Jinchūriki, the black and white chakra needs to be balanced at exactly an 8:2 ratio or it will backfire. The ball can be fired in several different ways: in sphere form, which can be detonated for a wave explosion; in the form of a dome-shaped blast, which flattens and erases everything around it; or as a concentrated beam of energy, much like in SSF2, which gives it explosive penetrative power.