Mm, that's true as well! Though, seeing as your Ditto were able to pull off an adequate human transformation, getting them to speak might not be too much of an impossibility. After all, there are rumors of Zoroarks, the evolved form of Zorua that I mentioned before, that can supposedly mimic a person's voice as well in their transformations. I've yet to see it for myself, but it sounds like it would be a very astonishing flavor to get to taste if it's true.

[Zorua, on the other hand, he's not sure of since the only one he's met is Luke's who seems to prefer not speaking (or is incapable of doing so) when it's in one of it's human transformations.]