User blog comment:ShadowDragon135/I'm Sorry/@comment-3244796-20111012005451/@comment-3244796-20111012011121

To balance the boss fight out, silly. Modern will fight all the enemies that were introduced in his era (Shadow, Perfect Chaos, and Silver) and Classic Sonic will do the same with his enemies (Metal Sonic and Dr. Eggman, who pilots both the Giant Mech and the Egg Dragoon).