Shadow the Hedgehog

Shadow the Hedgehog (, Shadow the Hedgehog) is a character from the series.

Origin
Shadow the Hedgehog, like Knuckles the Echidna, is a rival of Sonic the Hedgehog. An artificially-created hedgehog known as the "Ultimate Lifeform", he made his first appearance in  as an antagonist who becomes an anti-heroic protagonist as the game progresses. Since his debut, he consistently holds second place as the most popular character in the franchise, trailing the eponymous character. Unlike his heroic counterpart, Shadow is a much darker character, willing to do whatever it takes to reach his goals. In later games, Shadow often appears as an anti-hero with inherently good intentions, even if his methods are violent and ruthless. He features in his own self-titled game, , released in 2005. After the conclusion to his story in this game, Shadow would continue to play roles in future games, mostly as a supporting character with a few playable appearances.

In Sonic Adventure 2, Shadow was created several decades before the game's events, by Dr. Eggman's grandfather, Gerald Robotnik, on the Space Colony ARK. He was the result of a successful government medical project in collaboration with the leader of the Black Arms, Black Doom, called Project Shadow, which had the goal of finding a way for life to be immortal. Soon after the project's completion, the government began to fear Shadow's power, and attempted to erase the project from public records. Fifty years later, Dr. Eggman reawakens Shadow in order to reactivate the Eclipse Cannon, a weapon of mass destruction built into the ARK. Sonic and his friends attempt to stop this plan, but both parties are eventually forced to work together to prevent the ARK from crashing into Earth. When the Biolizard, the prototype Ultimate Lifeform, fuses together with the ARK to become the Finalhazard, Shadow partners with Sonic and uses the power of the Chaos Emeralds to become Super Shadow, fighting to stop the new threat.

In the Sonic series, Chaos Control is a technique that allows the user to warp through space and stop time through the manipulation of the fabric of space-time. The user needs at least one Chaos Emerald, and the strength of Chaos Control is increased with each Chaos Emerald added until being maxed out with all seven. Shadow was one of the first to utilize the technique, with other characters also learning how to perform it later on. In Sonic Adventure 2's two-player mode, Chaos Control can be used by Shadow to stop time and "freeze" the opponent while he moves at normal speed. Chaos Control can also be used to slow down time in Sonic Heroes, and when fighting against bosses in Shadow the Hedgehog. In the Super Smash Bros. series, Shadow appears as an Assist Trophy and uses Chaos Control to slow down opponents of the fighter who summoned him. In most Sonic games, such as Sonic Adventure 2 and Sonic Heroes, Shadow is shown using the green Chaos Emerald to perform Chaos Control, which is also portrayed in his appearance in Ultimate.

As an Assist Trophy
Shadow appears as an unlockable Assist Trophy character in Brawl and uses his Chaos Control ability to slow down everyone except the summoner (similar to the effects of the Timer item, though with a shorter duration, and without the risk of it backfiring). Shadow the Hedgehog is unlocked when the player unlocks as a playable character.

In Brawl, Shadow the Hedgehog is voiced by Jason Griffith (who also voices Sonic) in the English version of the game since his own game and the anime Sonic X, and Kōji Yusa in the Japanese version, who has been continuously voicing Shadow since his debut in Sonic Adventure 2.

As an Assist Trophy
Shadow retains his role as an Assist Trophy that slows down time in SSB4. His distortions are more visually apparent in this game, appearing clearly in the foreground. His own visual aesthetics were also altered to be just as bright as in his home series, as well as his mouth's placement being more to the side of his muzzle instead of right below his nose, matching. This time, he is voiced in English by Kirk Thornton, who succeeded Jason Griffith in voicing him in the Sonic series since 2010 with ; Kōji Yusa reprises his role in Japanese and just like Sonic, Shadow has gained voices in other languages as well. His non-Japanese voice clips are recycled from .

As an Assist Trophy
Shadow returns as an Assist Trophy and now holds the green Chaos Emerald. As in Brawl and SSB4, Shadow performs Chaos Control to slow down the opponents of the fighter that summoned him. In addition to slowing down opponents, near the end of Chaos Control he will trigger a brief second phase that completely stops the opponents. His visual distortion is green and is much more apparent with lightning also striking around him. He cannot appear on 3D Land, Flat Zone X, Magicant, Midgar, Mute City SNES, Pac-Land, Spiral Mountain, Super Happy Tree, and WarioWare, Inc.

Spirits
Shadow appears as two different primary spirits. Super Shadow can be obtained by enhancing the Shadow the Hedgehog spirit at level 99.

Shadow's Spirit Battle uses a puppet fighter and is fought on the New Pork City stage's battlefield form. During the battle, Shadow appears as a hostile Assist Trophy while the Timer item appears, referencing Shadow's Chaos Control ability, which allows him to slow down and temporarily freeze time while holding a Chaos Emerald.

Trivia

 * Much like Sonic, Shadow appears in the most Smash games out of all third-party Assist Trophies, having appeared in all games since its conception.
 * Despite his trophy and official artwork sharing the same pose in Brawl, the mouths on the trophy and artwork are in different positions.
 * Even on a fast moving stage such as Delfino Plaza or Rumble Falls when sped up, Shadow's effect will not stop even when he goes off the stage.
 * Shadow's trophy pose in Brawl resembles his artwork for Sonic the Hedgehog (2006). Similarly, his trophy pose in SSB4 resembles his artwork for Sonic Rivals.
 * Shadow is currently the only Assist Trophy to change voice actors between installments, switching his English voice actor from Jason Griffith to Kirk Thornton between Brawl and SSB4.
 * Shadow is the only Assist Trophy to appear in an intro movie, with his cameo in the intro of . Though Riki also appears, he is only present as part of Shulk's Final Smash, Chain Attack.
 * Shadow (in Smash 4 and Ultimate) and Knuckles are the only Assist Trophies to have voice actors in languages other than English and Japanese, being also voiced in French, Spanish, Italian, and German.
 * In Ultimate, when Shadow poses after finishing his Chaos Control, the Chaos Emerald can still be seen in his hand. However, in his render on the official Ultimate website and in Training mode (which uses the same pose), the Chaos Emerald is not there.
 * Shadow only disables normal hitboxes when affected characters are frozen in time. All other hitboxes that happen to be active when frozen remain active until the character is unfrozen. This creates several unintended side effects like counterattacks not functioning properly, attacks with reflective and absorption properties lasting much longer than normal, and characters remaining invincible and intangible for the entirety of their frozen state under specific conditions.
 * This also applies to Villager & Isabelle's Pocket.
 * Shadow is the only Sega Assist Trophy to not share a move with a playable character. Knuckles shares the Homing Attack with Sonic, Rodin shares the Wicked Weaves and After Burner Kick, and Akira Yuki shares the Tetsuzanko with Bayonetta as well.