There are so many characters begging for a redesign...but not these three. Harley, Poison Ivy and Catwoman are so symbolic and perfect the way they are!
That said, this is just a try to make them look a little more "modern". The way I see, each one of them would be represented by a fashion style.
I see Harley Quinn as this inconsistent and irresponsible girl haging out with the wrong gang. Not a hooker, not a mean person, just a very very confused kid. "Crazy" if you like. Her style would be similar to what Harajuku girls wear.
Poison Ivy is the kind of stylish woman, a Pin-up babe, who happens to control plants.
My shot at Selina, my favorite Gotham girl, is something more like a "professional thief", equipped with all these high tech gadgets and mountaineering gear.
But hey, that's just me