Nadian
(You can find them on wild Geodudes and you can obtain one in-game in the city with the seventh gym, trading a Medicham for a Haunter.)
I've decided that both of my Timid Deoxys might be available for trade, but their IVs are pretty sucky. I'll wait until after the Deoxys Event is over and I've decided on what I'm going to keep and what I'll need to look for.
3nodding So, the trick is having a Ditto of every nature with an everstone on all of them... Sounds like I've got to be patient with my perfect team training.
Since the only ditto that I have is a hasty nature. That means I should get another 19 Ditto of various natures. (Quirky, Bashful, Serious, Docile, and Hardy result in the same stat modifications, so only one of all of those stats would really be necessary.)