Errgh, Wrong. Mewtwo was created as a clone as Mew, and Shadow's original Idea (I think) was more based on as a clone of Sonic.
Or a creation that coincidentally is a hedgehog.
Frankly, I did find it weird that Shadow was a Hedgehog at first. Now I prefer him over Sonic. oh the Irony. (And yes People, I do play Sonic The Hedgehog still. Not any weirder though then posting on a Pokemon Board, My opinion.)
Official Co-Leader and Supreme General of Team Miror Infinity. Shadow Pokemon: Tyranitar.