There is no such thin as mew 3.
Mew 3 does not exist
No
Nope.
There is no Mew 3.
No! Sorry
No, you can't. You catch a mew, it evolves into mewtwo and that's it.
There is no such thing as mew three
Episode 3
3.
Nope, there isn't. Sadly...
You have to migrate mew from generation 3 as of now.