Dark Mechawful's are the darker versions of Mechawfuls appearing in Mario & Luigi: Bowser's Inside Story and its remake, Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey.
Dark Mechawfuls appear as overworld enemies. Only Bowser can fight them. Their attacks include punching with their cannonball arms or firing a star-shaped laser. In the original game, Mario and Luigi cannot fight Dark Mechawfuls but only their normal counterpart; however, with cheats enabled and fighting them, their punch dash attack works normally and can be counterattacked, but if they perform their purple laser attack, it puts the Dark Mechawfuls in an unstable state where the game thinks their heads are out of their body and they perform the attack that only Mario and Luigi can encounter. The red laser zigzags into different positions three times and shoots out stars very slowly one by one, then the game proceeds to be softlocked after the attack is finished.