This special type of Koopa Troopa can actually use powerups. I'm not talking about just the Super Mushroom, I'm talking about ALL the power-ups. Here is a list of his transformations: (click on the power-up to get linked to the page for that koopa transformation.)
Mushroom : Super Koopa Troopa, which can ground pound you if you get too close.
Giga Mushroom : Giga Koopa Troopa, which acts like Giga Mario, destroying anything in it's way. Unlike other Power-up Koopas, this one needs to be ground pounded 2 times before it reverts back to a normal Koopa Troopa. It is so powerful that it acts like a mini-boss.
Fire Flower : Dark orange koopa instead of yellow (and can shoot fireballs)
Ice Flower : Koopa's hue turns blueish, and it can shoot ice and freeze mario.To break the ice, you need to keep tapping A.
Star : Shell becomes rainbow, and you can't defeat him for a short amount of time.
Mini Mushroom : Mini Koopa Troopa, which can jump on you and make you take damage. Keep pressing A to shake it off.
Super Leaf : Can turn into Tinoo-Koopa, which looks similar to Acorn Koopa, but instead can swing their tails and make you take damage. If you somehow manage to push one off an edge, they will float for a while before dropping to their doom.
1-up Mushroom: If a Power-Up Koopa somehow eats a 1-up Mushroom, they will reward you with it once you stomp on their head.