Ehh. . . the Penguin is *not* smarter than Batman. He likely thinks of himself as such, sometimes, but this is mainly an artifact of his ego. If anything, I'd say the Penguin is defined by being a petty, cowardly bully, who is very adept at being the biggest fish he can in a comfortably small pond.
Which is to say, he works best when he is not actually much threat to Batman in his own right, and folds once serious pressure is brought to bear, but makes things worse for everyone before that happens. He's a second rate Kingpin, who is nonetheless pretty good at being a second rate Kingpin. And any resentment for this status he feels, he takes out on those weaker than him.