Billy, the Subterra brawler, has a very similar appearance to Ash Ketchum in Pokémon. Billy wore Ash's Indigo League hat from Season 1 in Pokémon, Billy throws a Bakugan similar to Ash's throwing style: a a backwards turn of the cap, then saying the command. On top of these things, Billy and Ash both have high, and particularly annoying voices.
The show has been criticized for being similar to Pokemon.