User blog comment:Soniczero000/Sonic x Mario: Mega Game War/@comment-4040842-20130312032350/@comment-6576725-20130312222011

The final boss could be the Egg Bowser a  gigantic robotic Bowser with Eggman's color scheme and mustache.The new team up arc could have bosses that are robotic versions of Mario enemies made by Dr.Eggman even a Mecha Mario that teams up with Metal Sonic for Mario and Sonic to face.