Kavaxas is supposedly the Nick version of the Warrior Dragon who sometimes is called Hothead, In the TMNT Archie Comics he was an Asian fireman who can turn into a giant anthropomorphized dragon, He even became a love interest for April in that comic series.
http://turtlepedia.wikia.com/wiki/Chu_Hsi
The fact Mikey just called him Hothead on the Nick series, I think its more a throwaway reference.