Blood Sugar is the primary weakness of Mobster Kingpin. Due to his Type 2 Diabetes, feeding him any sort of sugar-rich substances, such as the ammunition of a Candy Mecha or some Grenades will allow all attacks to do more damage. An Ace Dick takes advantage of this by constantly lobbing said grenades into MK's mouth, which, by their dual nature promptly turn into chocolates.
Unfortunately, should Death be distracted by a game of Sudoku or some other nonsense when MK arrives, MK may come back from the dead and give himself an Insulin Shot. If that happens, his one exploitable weakness will change to Emotions, and any attempts to raise Blood Sugar will have no effect besides MK revelling in the sweetness for the first time in many, many years.