From a practical standpoint, I'd have to say Robo Overclocked is amazing! When well-built (for Robo, aside from being tanky and having high attack, being well-built also means being equipped with mostly beam moves), she's the only character (that I've tested) that, with Fight Assist turned on, is able to single carry in a number of Prize Fights even in high streaks, and also in some Accursed Experiment fights.