One can look over the Midnight Crew and reasonably presume that they're an Evil Counterpart to Team Sleuth, with Space Slick as Problem Sleuth's, Clubs Deuce as Ace Dick's, and Diamonds Droog as Pickle Inspector's. This leaves Hearts Boxcars as the odd man out, and so I submit that he is, in fact, Mobster Kingpin's Evil Counterpart. Though the play as much as counterparts as the do opposites...