Sonic eventually broke into insanity after a final straw where Amy forced him to marry her mercilessly, and even threatened to beat him to death. Suddenly, Sonic overcome his fear of the Piko Piko Hammer, snatched it out of Amy's hands and smashed himself until he was nothing but a bloody mess. When Amy calmed herself, she looked at the deceased hedgehog, only to go crazy again. In the middle of her madness, she morphed the Chaos Emeralds into the Super Emeralds with the Master Emerald and used all the powerful negative energy to transform into Shadow Amy, and became invincible, even going as far as ruling the world and reshaping in a twisted image of Sonic. The only ones who escaped her wrath were Tails, Shadow and Blaze. They created a serrum that would bring Sonic back from the dead, for they needed his help. However, these four would not be alone. Out from a portal comes Luigi, a blue Kirby, Diddy Kong and a Pikachu in battle armor named Rechter. They heard that the dimension of Sonic and his friends is suffering a universe-wide collapse, because Shadow Amy has torn the planet that Sonic and friends live on to pieces, something which Dr. Eggman did twice before. With a new band of freedom fighters born, Sonic, Tails, Shadow, Blaze, Luigi, Blue Kirby, Diddy and Rechter set off into the twisted world to stop Amy from harming the universe any longer.
Shadow Amy appears in Sonic Final Battle Genesis as an android modelled after Amy Rose called "Amedroid Rosebot" as a reference to the name of her namesake. She is one of the main antagonists for Team Blossom (Amy Rose, Fiona Fox and Bunnie Rabbot) and works with Metal Sonic, Tails Doll and Metal Knuckles.