umm, a couple of questions:
1) how do you gauge the relative intellects of a couple of comic book characters, one of whom is labelled a genius and the other relies exclusively on his intellect to design and implement strategies for defeating foes of inordinate physical superiority over him?
2) isn't Batman a "superhero" because of his Batman persona rather than his Bruce Wayne persona? one is rooted in utility belts, electronics, technology and strategic thinking, the other is a physical being, a human being at "peak human" levels of athleticism and health.
a straight up fight should always go to Beast, but in character, in comic, Batman should win the majority. the Beast may be clever, but Batman's defining characteristic is strategic thought and adaptation, he'll find a way... (genetically modified fleas, for that thick blue Beast-y coat?)