I got a modest spiritomb now. Now I only need a Relaxed Snorlax that has the move curse. But I'm doing that myself. I'm trying to do at least one pokemon of each type fully trained in IV's at least up to lv 80, with as few type weaknesses as possible, with natures that benefit their base stats, and with move sets that are both strong and cover as many possible weaknesses as possible, and for some pokemon different ability. It's easier than it sounds.
Anyway, of the 3 natures of ditto I don't have, relaxed, calm, and docile, I only will need the first 2 because Docile doesn't do anything. I can give you a spiritomb and whatever else you want. Between all my games, I have probably got one or more of everything.