Kinda, but not really.
No but your probably referring to Mephiles, Shadow's Shadow
There is Sonic, Amy, Shadow, Silver, and Mephiles the Dark, who is actually a dark spirit in the form of a hedgehog.
Mephiles the Dark is half of the god Solaris, combined with Iblis. He and Iblis were separated when the Duke of Soleanna tried to harness the Flame of Solaris' powers but failed. He was then sealed by Shadow the hedgehog in the Scepter of Darkness, which explains why he hates Shadow. He then comes back as Shadow's shadow and tries to destroy the world.
use memory shard blue
Yes he is, Well he is animorphic . Shadow is also a hedgehog, Amy is too And Silver!!! but not Mephiles...
Mephiles the dark
No mephiles is not shadows twin in the game sonic the hedgehog 2006 he has two forms, an ice form and a smokey form he is released from the septer of darkness and takes shadow's shadow causing him to look like him. shadow and mephiles are enimes and have no relation or connection at all.
Mephiles the Dark was a character and was one part of the being that was the primary antagonist from Sonic the Hedgehog. Mephiles has three forms; the first and original was a dark, blackish-purple formless ooze or gas with some gaseous qualities. In his second form, Mephiles appears almost identical to Shadow the Hedgehog, aside from having green eyes, no visible mouth, and the fact that everything that is red on Shadow is gray on him. His third form (and his preferred one when he uses his abilities) was a crystalline, anthropomorphic hedgehog form resembling the appearance of other hedgehogs in the Sonic series, such as Sonic himself; in this form, he has no visible nose, mouth, or feet. His name was based on the one of the names of Mephistopheles related to the legend of Faust.
mephiles
Shadow has quite a few quotes, a popular one is "If the world chooses to become my enemy....I will fight like I always have." Which was stated against Mephiles in Sonic the Hedgehog 2006.
The Fountain of the Priest is a symbol of Soleanna's religion, it was also used by Shadow the Hedgehog to create a new Scepter of Darkness to seal Mephiles in.
Shadow meeting Mephiles is just a rumor