BOLD prediction

I think its radioactive man in disguise . I think after we get all the phase 4 prizes he will ask us to join him his evil plot then when we refuse we fight him like we would a felon but he has ten hearts instead of three. After we beat him it is revealed that is is radioactive man and he was doing this to test how true of a hero we truly are. Then we get him as a playable character as the grand finally of the event. Thats just my guess but I do like your idea a lot more and I do think we will get Sideshow bob but I just dont think this is when we will get him. BUT if you remember all the villeins are being brainwashed by mind control and I remember in one episode Sideshow Bob brainwashes Bart to kill Krusty so it is possible... I guess we will have to wait and see.