Different dragons have different qualities during the brawl, which are indicated by their colored circles.

 

Red = Furious Dragons have better attacks.

Green = Protector Dragons have better defense.

Purple = Cunning Dragons have better special attacks.

Blue = Swift Dragons have better speed.

 

The Swift Dragons have a shorter cool-down time than the other dragons. If your opponents have some of these dragons in their team, they will have more turns.