you can't be serious...
There is no way I can see Frankie Muniz as Robin...
unless he played Tim Drake and not Dick Grayson, then maybe then I could possible see a fit, but thats stretching it for me.
Or they could make him the 2nd Robin, Jason Todd and kill him off in the movie.
That would make it interesting.
As for Bale, i've only seen him in Shaft and American Psycho. He looks like he could pull the dark aspects out of The Dark Knight without a problem. The other softer side is what i'm unsure about.