Mysterious cards came down from the sky one day. Capable of summoning powerful creatures from another dimension, they became the centerpiece of a new game called Bakugan. The game gained instant popularity among children and teenagers, with the best of them competing in a worldwide ranking. Meanwhile, war for domination over Vestroia, the homeland of Bakugan cards, rages on. Invaded by the White Dragon Naga and his servants, the Doom Beings, the realm becomes increasingly destabilized. Dimensions begin to merge and many Bakugan players come to realize that their pastime is not merely a game. Danma Kuusou, one such Bakugan player, intends to become the World Ranking's leader someday. However, during one of his fights he experiences a vision of a clash in Vestroia. The fight suddenly moves to Earth, where Danma comes into possession of a talking, mighty fire Bakugan, Pyrus Dragonoid. He soon gets dragged into the conflict, and together with his Bakugan Brawlers team, must traverse the dimensions and restore balance in a ravaged world. [Written by MAL Rewrite]

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. [Written by MAL Rewrite]

After returning from the feuding realms of Gundalia and Neathia, Danma Kuusou and his companions continue their lives on Earth. Now, a year later, the virtual reality world of Bakugan Interspace has finally recovered from the alien invasion and has once again become a place for brawlers to gather and challenge themselves. It turns out, however, that whenever Danma's Bakugan, Pyrus Dragonoid, unleashes his might in battle, the Interspace experiences new disruptions. Unable to harness the incredible powers granted to him by Code Eve—the Bakugan Mother spirit—he struggles to maintain control over the Mechtogan contained within him. When it goes out of control, the mysterious mechanical entity wreaks havoc on the battlefield, attacking friends and foes alike. To make matters worse, Bakugan Interspace is at risk of being infiltrated again. An unknown mastermind is sending mutated Chaos Bakugan into the system in order to brainwash brawlers and take control of the virtual realm. In anticipation of the inevitable confrontation, Danma must find a way to keep the Mechtogan's destructive force at bay and rally the Battle Brawlers once again. [Written by MAL Rewrite]

Second season of Bakugan: Battle Planet. The series follows pre-teens Dan Kouzo, Shun Kazami, Wynton Styles, Lia Venegas, and their dog Lightning. They are known as the "Awesome Ones" and make videos on the website ViewTube. Eventually, they stumble across a race of battling biomechanical creatures called Bakugan. They soon befriend the Bakugan and begin to battle each other with them, all while defending their neighborhood from thugs who use the Bakugan for malicious purposes. (Source: Wikipedia)