Write a hypothetical plot synopsis for a third Sonic Adventure game.
Sonic and his team find themselves in the middle of an intergalactic war between two powerful alien races, the Mysticons and the Dracos. The conflict has escalated to such a point that entire planets are being destroyed. To stop the destruction, Sonic must travel through various galaxies and battle against both the Mysticons and the Dracos while trying to uncover the truth behind the war. Along the way, he will encounter many allies and enemies, including Tails, Knuckles, Cream, and other characters from the previous games. As the story progresses, it becomes clear that the true enemy is not just one race but a combination of them all. In order to save the universe, Sonic must use his skills, abilities, and teamwork to overcome their combined forces.