Mike from Mii-gamer:
Like in Brawl, Sakurai will be providing daily updates on the development progress of Super Smash Bros for Wii U/3DS through Miiverse.
Today's update is a screenshot of the Yellow Devil from the Mega Man Series. We can see the yellow devil dismantling itself to attack Sonic and Mega Man. It is still unclear whether the Yellow Devil is a stage hazard or a boss battle.