From the Super Mario Wiki
The Dark Koopatrol (or D. Koopatrol) is the stronger version of the Koopatrol and the strongest type of Koopa in Paper Mario: The Thousand-Year Door. The Dark Koopatrol is one of the most powerful enemies in the game, with a very high amount of HP and Attack. These elite Koopa soldiers wear a spiky metallic helmet, so as not to be jumped on by Mario, and also have intimidating spikes on their shell. Much like the Dark Craw, the first Dark Koopatrol encountered, named the Koopinator, is found in the Glitz Pit. He is the last fighter Mario must defeat before his battle with Rawk Hawk. Dark Koopatrols attack by charging at Mario and his partners, or by using a move similar to Power Shell. Unlike the regular Koopatrols, they are unable to call in reinforcements. They can even increase their Offense by charging their attack by +5. The one weakness they have is that they can be flipped onto their shells like normal Koopas through the use of an Quake Hammer attack or Mario's jump if he's wearing the Spike Shield badge.
Not counting bosses, Dark Koopatrols have the highest amount of HP in the game.
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