Here are the two sides of the same poster. Going with the "double sided" theme of Unleashed, this makes a lot of sense. This is a magazine-insert/pull out poster. One side you can see a very nice render of Sonic at Chun Nan with a dragon in the background. The other side shows an aggressively positioned Werehog with the dragon more to the foreground. Though the 2nd side is supposed to be night-time the effect is still pretty bright. This is a great poster that's hard to get bored of because you can always flip it! 

This poster has been confirmed to have been in AT LEAST the Canada Version of GamePro Magazine. But, with someone in England obviously owning it, either GamePro released there too, or, they shared the poster with other magazines. Does that mean USA GamePro had it too? Which issue had it in there as a bonus item? You can write in for credit if you know where this 'pull out poster' is.