The original depiction of Harley Quinn from Batman: The Animated Series is certainly wearing skin tight clothing. She certainly has an unrealistic body shape. She is not, however, any definition of nude. At this stage of the character's design, her body type is more a product of exaggerated art style than objectification.
Harley's next depiction, in Batman : Harley Quinn, takes the same design a step further into sexual objectification. She's still covered, but she is much more bent at the waist than before, and Joker's mere touch seems to have put her in the throes of orgasm.
By Batman: Arkham Asylum, Harley has gone from surprisingly clothed to surprisingly not a hooker. The intended realism of the Arkham series makes a woman who was once a doctor of psychiatry into a strange amalgamation of a prostitute and a nurse.
It's sequel, Arkham City, doesn't make her outfits any more modest.
At a certain point in the game, she is found tied up by one of Joker's henchmen. Throughout the game, henchmen make reference to wanting to rape Harley. Although these two concepts are not presented at the same time, it's hard not to link them in your head. The worst of it is that Harley being tied up is presented as a positive for Batman without any regard for what it means for her. Harley is a villain, villains aren't people, so it's okay to imply the rape of a villain (or so we are told) - except she's not evil. She's a medical professional who does evil things and dresses in tight, provocative clothing in order to avoid the wrath of her abusive, mentally ill boyfriend.
Harley isn't even the only Batman character objectified for being a woman. Poison Ivy is actually nude for much of the Arkham series, wearing only a button-up shirt that is only buttoned enough to hide her nipples. Due to her part-plant DNA, Ivy's genitals are even in full view at all times, taking the role of a leaf that is the spitting image of a human labia. The other leaves are grown on her body in such a way that suggests panties, but that does not change their status as a part of her body, even a best case scenario presents them as her pubic hair.
Catwoman, who is supposed to be a master of stealth, has decided that massive cleavage doesn't defeat the practical thievery purpose of an all-black bodysuit.
What about the women of Batman who are not half naked?
Which one? Oracle, the one stuck in a wheelchair and treated as a secretary? The former Batgirl who was shot in the spine by the Joker, thus going from a great example of non-objectified woman to a 1940's stereotype of woman's role?
Or maybe you mean Nora Fries, the cryogenically frozen wife of Mr. Freeze? She's a highly sexualized block of ice that's stolen and traded in the same way one might do to a statue.
Certainly the woman who was actually turned into an object hasn't been objectified.