This is dumbest enemy ever (other then goombas)in a video game. They can be found in the Mushroom Kingdom. The green koopa is not intelligent at all. The reason being when walking toward a cliff, gap, edge ect. they will just fall to their deaths. Scientists believe that this is a birth effect. They say the ones with the green shells have it. The regular koopas, red koopas, are far more intelligent. As they don't fall off ledges. In Mario Kart unlike the green koopa shells, the red ones seek the other racers, while the green one just goes straight and bounces of walls. So the green koopas suck.
The green koopa killed himself by accidentally falling off a ledge, before Mario had the chance.