Bakugan

Bakugan Battle Brawlers is a Japanese action adventure anime television series produced by TMS Entertainment and Japan Vistec under the direction of Mitsuo Hashimoto. The story centers on the lives of creatures called Bakugan and the battle brawlers who possess them. Consisting of 100+ episodes. The latest season of Bakugan, Gundalian Invaders,  Is currently airing, and the fourth season,  Mechtanium Surge , is to be released soon.

Plot
In the parallel world of Vestroia, a power-hungry Bakugan (a small marble magnetic sphere which when thrown on a gate card turns into a highly strong and powerful warrior) named Naga decides to absorb the energy of the two opposing cores that preserve the balance and peace in Vestroia. However he absorbed too much power and energy found within the Silent Core, the source of negative energy. The Infinity Core, the source of positive energy had been absorbed by Wavern.

The story centers on five friends who find metallic cards which have fallen from the sky or to be more precise, Vestroia itself. They name themselves the Bakugan Battle Brawlers and consist of seven children: Dan, Shun, Runo, Marucho, Julie, Alice, and later Joe. Together they learn more about the origin of the Bakugan, Vestroia, the game involving them, and the battle against Hal-G, Masquerade and Naga.

In  New Vestroia,  Dan, Marucho, and Shun are called to the newly restored Vestroia to stop an evil group known as the Vexos who invaded it. They allied with three new brawlers named Mira, Ace, and Baron in order to stop the Vexos from taking over New Vestroia, and possibly, the whole universe.

In  Gundalian Invaders,  Dan, Marucho and Shun get caught up in a war between two different alien factions in another universe, and teaming up with three of the top brawlers from Neathia, Fabia, Ren and Jake, in order to stop the evil Gundalian Protectors, the Twelve Orders from destroying Neathia, and possibly, Earth.