I found animation error in Bakugan Gundalian invaders episode 21,in this episode at the beggining Drago is Pyrus Helix Dragonoid,and not Pyrus Lumino Dragonoid that is the drago he was in previous
Episode 21 - Bakugan|FULL EPISODE|CARTOON POWER UP - YouTube
Bakugan New Vestroia Episode 21 Japanese Dubbed | 爆丸バトルブローラーズ ニューヴェストロイア 「21」| DVD RAW Ripped - YouTube