That's what I've read on Gamespot and Gamewinners.
Here's a link that links you to major Spoilers about the SSE.
Major (SPOILER)I really don't like how they made Sonic appear at the last second without him enduring a lot of harsh trials like the other characters did. It's quite a biased thing for Nintendo to be doing especially with a character they don't own. They almost make it seem like all the other characters and what they did don't matter since Sonic just takes care of the Final Boss himself and frees practically everyone else from being in their trophy form. He doesn't deserve to be the hero, not after doing anything until the final boss while almost everyone was helping out fight against the Subspace Army. This is exactly why I didn't want Sonic in Brawl.