The only way to get it besides move tutors is by using the Dream World. Bagon can be found in the Rugged Mountain area. The Bagon there have their Hidden Ability (Sheer Force) and will know Outrage. So all you need to do it level it up until it is a Salamence, and it will get Moxie.
However, unfortunately the Dream World has been shut down for the release of X and Y, which means there is no way to get a Salamence with Outrage + Moxie besides trading.