No. Mewthree only exists as a fan hack. You cannot find or catch it in any of the legitimate games.
you can only get mewthree in leafgreen firered, but you could migrate... mewthree is a fake Pokemon is it worth the chance of ruining you game ?
Mewthree is fake, REPEAT MEWTHREE IS FAKE >_<
There is no Mewthree period
There is no Mewthree
There is no such thing as Mewthree.
go to google images, and then type in mewthree/mewthree x
There isn't a "Mewthree cheat", since Mewthree doesn't exist.
There is no such Pokemon as Mewthree.
There is no such thing as a Mewthree.
You can not get a mewthree without hacking into the system.
Mewthree doesn't exist!
Mewthree is a fake Pokemon, it was made to be a hoax and it dragged alot of people in and sadly the only way to get this mewthree is by owning the ROM version of Pokemon and putting it there but so far the only way you could do that is if you hacked the ROM itself