Baseline (Widescreen) Solution & Issues
For the record (yeah, I'm sorting out old screenies today...) : Motocross Madness 2 is natively Hor+ in widescreen resolutions.
Due to the default camera position/angle during the rider's initial idle stance gameplay may be Vert-, but it is really Hor+ as soon as your bike gets moving - which should be practically most of the time. All different cameras are Hor+.
Ultra/Super-Wide (21:9/32:9) Specific Solution & Issues
Eyefinity / Surround Specific Solution & Issues
The game is supposed to support at least 3x 1024x768 through SGU, but this has yet to be confirmed. (TripleHead is afaik unsupported, which is odd since MCM2 appears as a supported title on the official Surround Gaming site... Any input on that, feel free to add it)
4k UHD Specific Solution & Issues