Dark Mechawful.5

A Dark Mechawful.5 is an enemy found in Mario & Luigi: Bowser's Inside Story. When Bowser, Mario, or Luigi destroy a Dark Mechawful and leave the ejecting head alone for a while, the head becomes a Dark Mechawful.5, gaining a new metal body. The differences between the two are: When Dark Mechawful.5 attacks, the numbers on their chest short out, causing the battle to get a bit more interesting.
 * Dark Mechawful.5 stops its timer on its chest, while the Dark Mechawful doesn't.
 * Dark Mechawful.5 has more iron plating, increasing defense.

Trivia

 * Their upper shield is more like a cape-holder. If it showed the back, there MIGHT be a solid-iron cape,but it will be unknown unless they feature them in a 3-d game.