Cats Don't Dance/WMG
Max is electrokinetic.
When Darla signals for visual representation that she's having an idea after her song-and-dance number "Big And Loud", Max promptly holds an ordinary lightbulb over her head. The bulb (connected to nothing but his gloved fingers) lights.
Later in the film, Max incapacitates Pudge the penguin by seizing him and rubbing him fiercely on his head, then sticking him to a metal beam with the static electricity. Normally, in cartoons, this works whenever both objects are suitably fuzzy; say, a Funny Afro, or a cat on a shag rug. But Max is bald [dead link] . Both events are explained if it is assumed that Max can generate and control electricity. In a very cartoony, physics-bending way, of course.
Darla Dimple isn't actually a child, she just looks like one.
Note her resemblance to Baby Doll, who is an adult actress with a rare condition that makes her look like a child even when she's an adult. She seems too smart, too vindictive to be a kid. (Or maybe this troper just can't handle hating a little girl. It makes her feel horrible.)