Much like Volcanion, Zeroara was found in the game files by dataminers, and that is how we know all that we do about it. In terms of any official info, the Pokemon Company hasn't actually released anything about it yet. If Zeroara follows the same pattern as the other datamined Pokemon before it, then it will be an event exclusive Pokemon, probably within a year. The only people who have Zeroara right now are hackers, so I wouldn't trust a traded one.
Sorry, but you'll just have to wait until it's info comes out and it is distributed officially.