Apparently, it's the "thing" now, so I have an idea I will share with you! (This'll probably be just a fan-fic.)
Basically, it follows the four main characters: Sonic and Silver, Classic Sonic (I'll explain later), and Shadow. The stories are as listed:
Black Doom returns. We know what that means.
Sonic and Silver
Sonic and Silver team up due to a certain someones that they are both persuing.
A mysterious enemy awakins Dark Gaia in the past.
Everyone meets... including the enemies.
PG: Well, Eggman's robot shoots.