ROB was an bot for the super fanicom (that's the SNES). It sold well in japan, but in North America, it just didn't catch on. ROB (which stands for Robotic Operating Buddy) was gray in American copies, and red & white in Japenese copies. So, when Nintendo made the game, they naturally made the ROB gray in North America, and red & white in Japan. On the US games, though, the staff ghost for desert hills (first course, flower cup) is the red & white ROB. ROB's color is carried through on wifi.
If you have a japenese copy of the game, but live in the US, your ROB will be red & white.