User blog comment:Plaguenumber3/Guard colab returns/@comment-3993996-20140508160329

With the expectation of Tyranids (for obvious reasons) Zoragons will ally with anyone to defeat Humans in some way. Eldar, Necrons and Dark Eldar would probably manipulate them (which is OK in my book) and they would "use" Orks. If its an attack on a Zoragon world than Tau probably won't be there (seeing as their on the other side of the galaxy) but otherwise they may ally. Zoragons would only ally with Chaos if they worshipped chaos themselves.

Overall if you want two antagonist races I'd recommend Necrons, either Eldar or maybe Tau to ally with Zoragons.