Metal Sonic

Metal Sonic is the secondary antagonist based on his placeholder Sonic the Hedgehog, but wants to instead defeat him mimicking his talents and abilities. Created by the evil genius Robotnik, Metal Sonic follows orders from the villain.

Past
Metal Sonic was created in Robotnik's Lab, meant as an identical foe to the hedgehog and making it easier to defeat said creature.

Sonic Mania
Dr. Robotnik has made contact with Metal Sonic on Little Planet, and with the might of the Phantom Ruby, Robotnik sends his foes (Sonic, Tails and Knuckles) to Stardust Speedway's past.

The heroes are back in present time, and discover a projector, showing off "Metal Sonic" hurting "critters". The heroes broke the projector, causing the real robot to appear and chase them down around a giant statue of Robotnik. He stops and uses a generator, powering several Silver Sonic's that help attack the heroes. The heroes successfully dismantle the bots and Metal Sonic sets chase again. They've reached the top and Metal Sonic transforms into his more powerful form, Giga Metal. Giga Metal pursues the team, destroying the path. The group attack the glass that protects the Phantom Ruby, causing him to return back to his normal state, yet also in defeat.

Sonic Mania Plus
Moments after Metal Sonic's demise, Eggman was able to locate Metal Sonic yet again and uses the Phantom Ruby the same way he did before. In the present, the heroes destroy a projector, leading to the same dilemma that happened earlier, and of course, he was in defeat.

Sonic Returns
In the forests of Angel Island, The evil badnik first sets foot behind damaged trees, in search of the Chaos Emeralds.

& Knuckles
The replica looks at his scanner, which shows a white Chaos Emerald flashing near him. Metal Sonic races to it.

Mighty And Ray
In despair, Ray looks at a poster of his friend, showing he is indeed missing. Ray then hears a ruffle in the bushes, skeptically, he looks around until he sees a strange blue silhouette of a robot, menacingly staring at him amongst the trees. It opens it's eyes and charges at Ray. Ray evades Metal Sonic's attack, which tears apart the missing poster. Metal Sonic turns his head around before turning his body around, viewing the squirrel. He stands and assaults Ray, until Mighty himself protects Ray with his shell, blocking Metal's clawed attack. Mighty slams Metal Sonic with a rock off to a distance. Whilst the robot tries to use his move, he gets the same rock to his face once again.

Although heavily damaged, Metal Sonic scans the white Chaos Emerald, which is carried by the armadillo. He quickly stands behind Mighty, Ray tries to call him out and Mighty turns, causing him to not see Ray getting punched out of the way. Metal Sonic, in a flash, choke holds Ray before hitting the ground. He demands the emerald, but Mighty tries to deny. He unfortunately does grant him the emerald. Metal Sonic throws Ray in Mighty's arms and he leaves with his objective completed. He is lucky to evade another rock and leaves onto Robotnik's Lab.

Metal Mayhem
When Sonic and his companion Tails find themselves inside, Metal freezes them and drops them, which causes the two emeralds to exit both heroes' possession. He zooms in front of Robotnik, who holds even more emeralds. He absorbs the emeralds' power, turning into his super state and attacks Sonic, who was excited to brawl against his rival. Mighty and Ray walk in the building, Mighty punches the replica away. From the wall, he launches off to the gathered heroes.

Metal Sonic first gets ferociously harmed, being attacked by Sonic's spin move, Ray's stomp, Tails' kick which is straight in the face and Mighty's uppercut. But he wins back with a painful swipe for Sonic, a kick which is blocked by Mighty, another harmful scratch to Tails and a punch at Ray.

Surrounded by the tired group, it looks like Metal Sonic might have one this battle, until Tails and Sonic have a plan. Sonic jumps at Metal Sonic, which he blocks. Sonic then starts spinning around him and Metal Sonic waits for the right moment to attack. During that time, Tails made a Freeze Box appear which also drops the badnik and frees the emeralds. Sonic spins with a final blow into Metal Sonic's lifeless body, but he later stands on top of the Master Emerald, equipping it's power...for a short time, because Knuckles attacks him in the head, being launched into Robotnik and out of the lab. Metal is now defeated, along with Robotnik.

From A. Rose
After their defeat, Robotnik and Metal Sonic bump into a tree and Metal Sonic falls on a Flicky. Robotnik angrily stands, kicks Metal Sonic, kicks him twice and leaves. Metal Sonic is left abandoned in the forest throughout the seasons, until the young girl Amy Rose appears. Not minding the bump in the middle of the island, she falls over it. She looks at the bump, and it turns around, looking at her. She realizes it's Metal Sonic and quickly steps back, afraid of it attacking her like most times. He turns his head back into the snow. Amy then saves Metal Sonic from a tree that almost falls on him. Metal Sonic looks at her again, but Amy attacks him. She attacks slower and slower until she feels guilty. She makes Metal Sonic stand, from his belly then evacuates a Flicky, who gives Metal Sonic a little kick, he falls from this. Amy then drags him through Angel Island, Mushroom Hill and Ice Cap, all the way to Robotnik's Lab. Amy makes Metal stand and puts a bowtie on his forehead. She rings the bell and gives a flower to Metal Sonic for Dr. Robotnik. She hides behind a rock. Robotnik answers the door and sees Metal's flower in his hand, together with the bow on his head. Dr. Robotnik looks around in confusion and takes Metal inside. Sonic is speechless whilst Amy is proud.

Appearance
Metal Sonic is an exact replica of Sonic the Hedgehog, but with a lot of changes. His head and overall body is indeed blue, but his muzzle has a grey color, which is the same for a part of his arms, his nose, his claws, his shoulders, a part of his feet and a part of his legs. His canals are yellow as well as the outer side of his hands and his belly which has a black center. He has black eyes with red pupils and red "shoe" with a white stripe.

Trivia

 * Metal Sonic is the only one who uses the chaos emeralds throughout the series.
 * Metal Sonic is modeled after Sonic the Hedgehog. Very rarely, he may even switch his alignment.
 * He is presented as a gift in "From A. Rose" to win over Robotnik to bring him back in.