In case your were wondering if Shadow was the real one or a Shadow android, this spells it out for you. He's real. He's not a robot. He's a gentically engineered artificial hedgehog created by Gerald Robotnik with Black Doom's blood.
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Yes, Shadow is alive. Eggman saved him with one of his robots.
True Super Forms maybe proof of his biology. But Mecha Sonic is also capable of being Super...