The Antagonists
Jason Todd, the Red Hood- Scott Caan
Taking center stage opposite of Dick Grayson as Batman is the black sheep of the Bat-Family, Jason Todd. Feeling angered and desperate that Bruce had not chosen him as his successor (I'd prefer it that the two had a falling out instead of Jason dying) Jason would take up the mantle of Batman's former arch-nemesis in the form of the Red Hood. Operating with the help of the sadistic Professor Pyg, Jason tries to bring a very premature ending to the new Dark Knight's reign, and to take the mantle he thinks he deserves. Scott Caan might seem weird to play the raven haired Todd, but I like his personality more for the character. Jason's a street tough; he's a brawler as opposed to Dick's circus aerialist. Caan has made a reputation of playing smash-and-grab, hit first ask questions later characters. Put to the ultimate test I think he could play Jason Todd immaculately.
Professor Pyg- Phillip Seymour Hoffman
Pyg would be the lesser antagonist of this tale, acting as a fetish freak in a pig mask who loves to cut people up and turn them into his perfect specimens. Acting to take a void in the Gotham crime world's seat of power, Pyg would turn to the Red Hood, who would know more about the Batman than anyone else. Capturing the beautiful Oracle in an attempt to make her 'perfect', Pyg would no doubt draw the attention of Grayson and Damian, leading to an inevitable confrontation between them and the Red Hood. I don't really see Pyg as having this booming voice or such a commanding presence to intimidate his subordinates or enemies, but just have the air about him that he's a sadistic son of a ***** who cares nothing about the human condition. I think Hoffman's perfectly droll and monotone delivery of lines (somewhat akin to what he did in MI:3) would be completely creepy enough to pull Pyg together perfectly.
The Joker- Adrien Brody
Yeah he doesn't show up in the comic, but if I were to do a film about replacing the Batman, you sure as hell bet that his greatest enemy would want a piece of the action. I'd take the Joker's role in this very much similar to his role in the Dark Knight Returns. He's near catatonic since the 'real' Batman died and wants nothing to do with this imposter. I think the thing that sets him off is the presence of the Robin he killed trying to take his mantle of arch-nemesis to the Batman. This Joker's quieter and ultimately much more psychotic than even Ledger's version, this is the true 'Devil-Joker' that Morrison originally pitched. I'll totally support Adrien Brody as this version of the Joker, one that's completely quiet for most of the film but who flies off the ****ing hinge when it's time for his grand appearance and the new Batman's Danse Macabre.