Dr Pamela Isley was a botanist who led a secret life as the eco-terrorist Poison Ivy. Unlike most of Batman's rogues, Ivy had little interest in money or power, but instead was obsessed with preserving plant life, and taking revenge on those who she believed had harmed it.
This is Poison Ivy as seen in "Batman: The Animated Series". In the original series, Poison Ivy's abilities are somewhat more mundane than they are in the comics. In the comics, Ivy is a metahuman villainess who is herself part plant, able to communicate telepathically with plant life, and also able to synthesize chemicals from her body at will, either as deadly poisons or antidotes to same.
In personal combat, Ivy is a skilled gymnast, and carries a miniature repeating crossbow on her right wrist, which she typically uses as a last resort - at least against people, since it's also useful for puncturing tires.
She is also a chemist. Combined with her botanical background, Ivy frequently concocts poisons, toxins, and serums designed to kill, transform, or protect, depending on her purpose and needs.
Poison Ivy has a unique genetic immunity from all forms of poison or toxin, including Joker gas.