This glorious golden mobile suit is the Hyaku Shiki. It was most famously operated by the AEUG pilot Quattro Bajeena during the Gryps Conflict. Originally, it was designed as a transformable mobile suit. However, defects in the frame made it unable to transform so it was released to the AEUG as a non transformable high performance mobile suit. The gold coating is actually a beam resistant coating, affording it better than average protection from beam weapons.

This is an older HG kit and, as such, its range of poses is a bit more limited than newer models. I think the gold plating really makes up for that though. It certainly sticks out in a crowd of gunpla. :)