Dark Koopas are found only in Toad Town Tunnels in Paper Mario. They are same to the Koopa Troopa, but they have their HP, Attack and Defense increased. Its HP is 8, the Attack is 3 and the Defense is 2. Sometimes, when a Dark Koopa spins to Mario, it will make him dizzy and he will be too dizzy to attack. When a tornado is on a Dark Koopa, Mario must attack it to avoid being dizzy. A partner must attack it when it is flipped over. Using Goombario's Headbonk or Bombette's Body Slam may be the best to defeat.
Defeating the Koopas lets Mario enter a pipe and the gate where he entered opens.
Paper Mario: The Thousand-Year Door
Dark Koopas are found only in the Pit of 100 Trials in Floors 31-49 in Paper Mario: The Thousand-Year Door. Dark Koopas have stronger attacks instead of causing dizziness to Mario. It uses the Courage Shell, Mr. Softener, and Happy Heart. Jumping is the best way to lose its defense.
Mario & Luigi: Bowser's Inside Story
In Mario & Luigi: Bowser's Inside Story, a different kind of Dark Koopa appears in the final battle with Dark Bowser. After his body grows large, he will throw a ball of dark enemies, including Dark Koopas. Dark Koopas go into their shells, and Bowser needs to punch them to knock them into the other enemies up ahead.