Watercolor and Gouache.
Batman sucks. Really. He's no fun, and over 60 years of comics, cartoons, and movies, he really hasn't changed much at all. Nor CAN he change. When he changes, it means the franchise is over. That stifles the creativity of the artists and writers, who basically have to rehash the same old points and stories over and over again. I can't wait until his copyright expires.
Then we'll have some REAL fun.