The sun and moon combine, and a giant monster is released. Knuckles got the worst of it,and he turns into a monstrous Wereidna, a beast form of an Echidna, but is much bigger than a Werehog.

This time, it not only affected Sonic, it effected Shadow, Shima, and Knuckles. He does the same thing as he did with Dark Gaia, but he fires upwards instead of downwards towards the earth. Eggman still wants to take control of the sun and moon, and thinks that using the Chaos Emeralds along with Master Emerald will help him control it. He gets to it, but is then trapped inside with it. Knuckles makes a break for the Master Emerald, but is more successful. Shadow and Shima go to his aid, but are captured, too. Sonic attempts to grab the Chaos Emeralds but is trapped inside a small capsule. They destroy the robots blocking their way and find Dr. Eggman's new space station in search of the Master Emerald and the Chaos Emeralds. Sonic, along with Shadow, Knuckles, and Shima, are infiltrating Dr. Sonic Unleashed 2 takes place a few months after Sonic defeated Dark Gaia. For the Wii, players can choose from three of the following controllers: the Nintendo Wii Remote, the Nintendo Gamecube Controller, and the Virtual Console Controller. Sonic Unleashed 2 is a 3D platform game for the Wii, Playstation 2, the XBox 360, and Playstation 3.

Sonic unleashed enemies