There was a thread on this show quite some time ago. I don't think Poison Ivy has been on the show yet, but Solomon Grundy has. And they ruined him. How the hell do you ruin Solomon Grundy? It takes a "special" type of talent to do that.
EDIT: After doing a minor amount of research, I found out that Poison Ivy has been/will be on the show. Here's a site with pictures of her:
Poison Ivy Bio