Watch Bakugan Battle Brawlers: Gundalian Invaders Online

After the final downfall of the rogue Bakugan Naga, peace was brought back to Vestroia. With the help of Danma Kuusou, his companion Pyrus Dragonoid, and other Battle Brawlers, the Infinity and Silent Cores were combined and the realm was recreated. However, New Vestroia will not be given any respite as humanoid alien invaders, the Vestals, arrive and conquer the Bakugan world in one fell swoop. Armed with a fearsome machine capable of restricting Bakugan into their ball forms, they aim to enslave the race as a form of entertainment. Now, the only force standing in their way is the Bakugan Battle Brawlers Resistance—a group of humans, Bakugan, and Vestals who oppose the idea of annihilating a sentient race. Led by Danma, they must venture into enemy-occupied New Vestroia and repel the invaders, to assure the survival of the entire world.

Bakugan Interspace is a virtual reality system, where players can brawl against each other and take part in tournaments. Initially designed to help practice and enhance Bakugan skills, it quickly became a meeting place for many enthusiasts. During one of Danma Kuusou's duels, the Interspace crashes, and he gets knocked out cold. Before regaining consciousness, he experiences a vision of Bakugan at war with each other once again. The explosion of energy that accompanied Danma's fight and caused the shutdown of the system sends shock waves across the galaxy, attracting the attention of the Twelve Orders, a Gundalian organization. They infiltrate Bakugan Interspace, looking for strong brawlers to join them in their upcoming war with another alien race, the Neathians. Danma and his companions—Shun Kazami and Chouji Marukura—soon find themselves caught up in an extraterrestrial war. However, distant as it may seem, the conflict threatens the very sovereignty of Earth and the future of the Bakugan race as well.

Bakugan Battle Brawlers begins with Danma Kuusou, a boy who invented the game Bakugan with his friend Shun Kazami after mysterious and seemingly random cards fell out of the sky. Together with their other friends, they form a team called the "Bakugan Battle Brawlers" in order to play this new game together. But unknown to these young friends, Bakugan is much more than a simple past time. Their game accidently sucks them into an alternate dimension called Vestroia, the home ground of Bakugan. Vestroia has recently come under attack by creatures known as the Doom Beings. This realm is balanced by the Perfect Core, which itself is formed by the Infinity and Silent Cores. When the evil Bakugan Naga attempted to take this great power for himself, he was unable to absorb the negative energy he wished to steal and found himself trapped in the Silent Core. Now, his presence within the core has destabilized Vestroia and attempts to merge with Earth as well as many other worlds. Danma and his friends must team up with individuals from other worlds who have also been drawn into this epic battle. As Naga is seeking the Infinity Core so that he may complete the Perfect Core in order to gain control of Vestroia, Earth, and all other worlds, time is of the essence in this devastating war of worlds.