bakugan battle brawlers

The first season of the Bakugan anime series, which details the first meeting between Vestroia and Earth and consequently humans meeting Bakugan.

The main characters are:

Kuusou Danma, The leader of the Battle Brawlers and a Pyrus user whose main bakugan is Drago.
Misaki Runo, a tomboyish girl who is a Haos user and later Dan's girlfriend.
Marukura Marucho, a young short but intellegent boy who is an Aquos user.
Alice Gehabich, a kind, gentle girl from Russia who is a Darkus user.
Julie Heyward, a cheerful girl who is a Subterra user.
Kazami Shun, a skilled ninja who is a Ventus user.

This tag implicates bakugan (learn more).