Shadow the Hedgehog

Shadow the Hedgehog is a character from the Sonic the Hedgehog and Sonic Universe series. Shadow is the ultimate lifeform created by Dr. Eggman's grandfather. Serving as a dark counterpart to Sonic, he possesses many of the same moves and abilities. He also has mastery over the space-time warping technique known as Chaos Control, allowing him to utilize chaos energy in a variety of ways.

Worlds Collide
Shadow was captured and transformed into Shadow Man by Dr. Wily and Dr. Eggman. His Special Weapon was the Chaos Cannon. He, alongside Rose Woman and Knuckles Man, later participated in the theft on a Chaos Emerald in Mega City, and encountered Proto Man and Mega Man, although a blue blur aided them in escaping. Shadow held the silver emerald and entered the newly-formed Warp Ring last, which he just barely made it through after being hit by Mega Man's Mega Buster.

Shadow Man and his counterparts later returned to the doctors with the emeralds, and were later dispatched when Sonic the Hedgehog and Mega Man, having joined forces, infiltrated the Skull Egg Zone with Miles "Tails" Prower, who had just reasserted his identity after his Roboticized Master self, Tails Man, as well as Proto Man, was defeated by the two, and destroyed Copy Robot and the Genesis Unit via Tails Man's ability, exempting Mega Water S who tried to retreat only to be shot by Proto Man. It and the rest of the Roboticized Masters, save for Vector Man, Charmy Man, and Espio Man, were then sent to take out Proto Man, although their fates were unconfirmed, to the Doctors irritation.

This Shadow Man, alongside Wily's Shadow Man, were later dispatched by the Doctors to confront Sonic and Mega Man, after some confusion as to which one to send. Eggman's Shadow Man then proceeded to attack Sonic with his Chaos Cannon, freezing the latter in place, but was ambushed by Mega Man and hit with Tail Wind, weakening his control over Chaos Cannon, before being hit with Sonic Blast, restoring him to his original form. Shadow then proceeded to return the favor by smashing Wily's Shadow Man to bits after Mega Man froze the latter with the Chaos Cannon he had copied. Shadow, however, had no interest in aiding his saviors further and warped out.

It was later revealed that Shadow had been searching for Rouge when he had been captured, requiring for her to find him. Sonic also managed to find Shadow with Amy's help (due to Amy having mistaken Shadow for Sonic once before).

In addition, Shadow attempted to fight off Napalm Man during the immense battle, although he was overwhelmed before Omega saved him, also revealing he had disobeyed Rouge's prior orders to stand guard near the exit portal. Shadow simply commented that he'll discuss it with Rouge when it is over. He then encountered Sonic after this, although he denied "leaving in a huff" and told Sonic to focus on aiding Rock (Mega Man) in stopping the Robot Masters after the latter promised to help save Rouge. He later fought off Hard Man and Top Man, although Sonic stopped them, causing Shadow to scold him. Shadow later encountered Rouge, or rather, Rogue Woman, and told her she shouldn't have encountered him at that point before being ambushed by Shade Man. Shadow later agreed to hold off the Robot Master army (which was constantly regenerating due to the time-distorting effects of the Skull Egg Zone) while Mega Man and Sonic rush to save Dr. Light.

After Mega Man discovered that Dr. Light had been thrown off the Wily Egg and was free-falling directly into the crater, Shadow used Chaos Control to save Light at the last minute, and then told Dr. Light to get someplace safe while he and the others cover him from the other Robot Masters. He later grew exhausted, alongside his allies, from fighting the constantly regenerating Robot Masters, but were saved by the timely intervention of Dr. Light's eight original Robot Masters. He presumably aided Light's Robot Masters to hold off the Robot Master army while Proto Man, Knuckles, Rush, and Dr. Light infiltrated the Wily Egg to back up Sonic and Mega Man.

Super Smash Bros. for Nintendo 3DS / Wii U
Shadow the Hedgehog appears as an assist tropy. He uses Chaos Control to slow down the opponents of the one who summons him.

Shadow also appears as a regular trophy.

Note
This is technically Shadow's second time regarding getting involved in framing Sonic for the robbery of a Chaos Emerald, having done so in his debut game.