Wow, a Wii yoga mat!
The Wii Step Balance Board came with a game Wii Fit that has exercises you can do, as guided by the weight sensor in the wii board. Some of the yoga poses though, should be used on a yoga mat, because you have to lie down on the floor.
So, a Sonic mat is perfect for that! The blue & white stripe mat has the modern Sonic word pressed into its texture (bottom) But that mat's not all there was to the kit, it also has a neoprene (rubbery fabric) step cover with Sonic, Knuckles & Amy on it, with a blue background. Protect the board with one, and your back with the other. It was called the "Wii Fit Character Pack". This was at Target stores in Australia.