From the Super Mario Wiki
Super Troopas are a sub-species of Koopa Troopas, and elite soldiers in King Koopa's army. They are larger than standard Koopa Troopas, and much stronger, but are rather dim-witted and somewhat clumsy. Super Troopas were only ever seen during a few select episodes of The Super Mario Bros. Super Show!.
The first appearance of a Super Troopa was in the episode "Mario and Joliet", where an individual one named Grunt was employed by King Koopa to trap Mario, Luigi, Princess Toadstool, Toad and Romano in a tower with Joliet. Grunt was then ordered to keep an eye on the captives, but was more interested in lifting weights. Toad and Princess Toadstool used the opportunity to convince Grunt that they had seen stronger Koopa Troopas than him, and ultimately tricked him into holding up too many weights. The concentrated weight of Grunt and the weights led to the floor breaking beneath Grunt's feet, which resulted in him falling through it.
The next appearance of Super Troopas was in "The Koopas Are Coming! The Koopas Are Coming!", where Redcoat Koopa had assembled a team of Redcoated Koopa Troopas to serve as soldiers in his Koopish Army. Amongst the standard Koopa Troopas that were employed as Redcoated Koopa Troopas were many Super Troopas. These Super Troopas fought against Mario's group, but were defeated rather easily.
The third and final appearance of Super Troopas was in "Star Koopa", were they had taken on the guise of Stormtroopas, along with many Koopa Troopas. They were only seen when Darth Koopa had ordered his Stormtroopas to invade the Flying Pizza, and fought against Mario's group with Lightplungers, but were eventually defeated. It is unknown if any of the Stormtroopas that were later piloting the Stormtroopa Starfighters in an attempt to defend Koop Star were Super Troopas.