[quote=@Burthstone]
[quote=@Silver Fox]
But ditto requires seeing the pokemon in order to transform into it xD
[/quote]

Only in the game.
[/quote]

I believe it happened in the anime as well (though it might have changed over the years. I only remember the first episode when Ditto was introduced)

Where the Ditto Trainer has to have 'guest' pokemon come up and Ditto transforms into that pokemon. (Thought at the time that Ditto failed at faces)

But dunno xD

So if I wanted a transforming Pokemon, I'd probably go with Zorua who could also turn human.