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 Sonic attacking Bowser’s shell. It seems that the shell protects bowser from his attack, hence why Sakurai said “Sonic, Failure” in miiverse.
Sakurai on miiverse:
“Pic of the day. Sonic, failure.”