Well, that's part of the inevitable problem of Batman, a street-level character, hanging out with JLA types, who are frequently pretty cosmic. Zee's power fluctuates a lot - sometimes she's really epic and dire, like "planet-warping League-level threat if she ever went bad" kind of thing, usually she's more middling, like Red Tornado-scale "could flatten a city if she wanted but it'd take her ten minutes" ... and when it's just her and Batman, she's "could feasably defeat as many as ten bad guys at once." Because how else does Bruce even begin to contribute?