Rumor Leaked Sonic the Hedgehog 3 Trailer description includes Shadow's Motorbike, a portly Dr. Eggman, but still no official Shadow casting announcement.

In essence, the Sonic Movie 3 trailer reveals Sonic, Tails, and Knuckles battling Shadow, who's cruising on a motorbike. Dr. Robotnik appears portly, sulking and munching on food in the footage. Additionally, New York City serves as a setting. Eagerly awaiting the trailer's official release!

Source