Doesn't Mew possess the move Transform? So mod is a Ditto pretending to be a Mew, or a Mew pretending to be a Ditto. My head hurts, I'll go lie down now.

Mod is clearly the pokemon you are least likely to try and catch. Yep, that’s what I am. Completely undesirable for catching. Just let me run around and do my wild and crazy antics. Hehe.