The Great Collision (グレートコリジョン, Gurēto Korijon?) is a mysterious event that happen twelve years prior to the start of the events of Bakugan Battle Planet. This event left various craters around the planet Earth, and, according to Veronica Venegas, disabled all electronic devices in the area during the event. Dan Kouzo was born on the same day that the Great Collision happened. 
While the Awesome Ones are investigating a crater left by the Great Collision in Pinpoint Park exactly twelve years after the collision, they witness a second event. This event features many blue lights, and any electronic or mechanical devices are disabled. Piles of goo are found lying in the crater after the event. These piles contained Bakugan, and touching these Bakugan, and by extension, touching someone who is touching a Bakugan, allows the viewing of the BakuCores that affect the Bakugan.
After this event, only children born after the initial Great Collision have the ability to see and properly use the BakuCores that are located in the Drome while brawling. Adults and anyone born after the Great Collision are still able to brawl with help of implants, but are unable to locate the BakuCores.
The goo pile that contained Drago