Mewthree is a fake pokemon that was created to fool people into believing it to be an
evolution of mewtwo.

The three lake pokemon of diamond and pearl, (uxie, mesprit, and azelf) is called the mew
three in sinnoh because of their tails and their psychic abillities.

there is know mew three ******.

And your mother.

Apparently you can get Mew 3 by giving a mew a metal coat and trading the mew for a mew 2.