An apparent leak via a snapchat image today and reported on Reddit appears to show the entire Super Smash Bros Ultimate cast including Shadow the Hedgehog, widely hoped for inclusion as Sonic’s echo character.
The image, which appears to show holiday promotional material for the Grinch, also includes a Super Smash Bros Ultimate Banner on which several additional characters feature not currently included on the official roster group shot.
A zoom-in on the image below appears to show Shadow the Hedgehog between two incarnations of Link, and in amongst other unannounced characters such as Banjo Kazooie, Ken from Street Fighter, and Mach Rider.
While it is possible that the image could be fake, the fact that it features amongst other promotional material would suggest this may be from a source with access to marketing not yet currently available.
As always, The Sonic Stadium will keep you up-to-date on all Sonic-centric information in Smash Brothers as it comes!