Bowser

Bowser is Mario's long-time archrival and a great threat to the safety of the Mushroom Kingdom. He's an overgrown turtle who is immensely strong, but he doesn't have a really big brain. He has yet to do battle in Mega Sonic Bros. AF, but he has once again an evil plan to take care of the heroes.

Personality
In Mega Sonic Bros. AF, Bowser somehow met up with Dr. Wily, who rebuilt Mecha Sonic and Mecha Shadow and created an all-new robot, Mecha Knuckles, which is much smarter and intelligent than the other mechas. In the currently released episodes, Bowser and Dr. Wily are mostly working behind the scenes sending their robots after Silver and Emerl, the Megaman Team and the Mario Team. The heroes still don't know who's behind the return of Mecha Sonic up to now and they still have to find out who rebuilt the robots.