What I'm taking from the movies is the situation (power vacuum) and tone ("super" characters rely on training and technology). I was thinking about using Poison Ivy specifically as an example, actually.
So, for one thing, empathizing with plants doesn't mean that she actually talks to them. She either thinks she does, or at the very least, puts their wellbeing above any animals in the city - making her the eco-terrorist type. She can also have access to all sorts of awesome science, like poisons in all shapes and sizes, and maybe she puts bugs/tracking devices in plants that people put in their homes/businesses. This is just off the top of my head, but I'm sure there are plenty of ways to make it work.
I'm happy to brainstorm, and I'm sure plenty of other interested players would be too.