In Super Mario Strikers, Koopa Troopa looks normal enough except his color which of course isn't a color he is usually and Koopa Troopa have nearly the same poses as Mario Strikers Charged on the Wii, although he's not the exact same, as you can see. What do you think does that? But honestly, let's look more carefully.
His eyes; His eyes are smaller and less openned. This thing doesn't make him feel the same. Second thing, his legs, they looks smaller.
And also, he also have a hole for his tail to pass, but we saw it really carefully on him.