I dont think Ivy hates MEN, She does have this thing for Bats in the early going
She posion Bruce Wayne, with her kiss, and only a 2nd kiss could save Wayne.
Batman was kiss by Ivy, Thus saving Bruce Wayne.(She of couse has no ideal she saved Wayne, but the kiss she put on Batman was not a fatal one.)
she's been mistreated by a lot of men through her life, a man is responsible for her transformation into poison ivy in the first place.
I think she just cares about a person for who they are, regardless of their gender (so yeah, I guess she'd be considered bi)
I don't think she's a lesbian, I think she hates all humans. She's one of those hippies, so she is all about the plants and nature and stuff. I think the reason she's with Harley is cause she knows Harley is naive and if you are a fan of reality tv shows, the women ALWAYS say "we're the girls, we have to stick together" to get alliances, and then backstab each other and ***** and moan and whatnot. So I think that is what Ivy was doing, gain trust and a sisterhood almost with Harley, so when she needs to, cut her loose.