She doesn't need anything. The two characters who beat her badly are just too good.
First off, stop respecting Wonder Woman's frame traps so much; otherwise you're just going to get put into a 50/50 every time you block a b1. Backdash, poke out, throw out the occasional parry or just block sometimes. d12 will beat any attempt to poke and although it is possible to hit-confirm, it's very difficult to do in an actual match. The majority of the time it's done on a read. Keep in mind that the overhead option only leads to a full combo if you don't backdash and there's no way to confirm that. This applies to backdashing on wake-up as well. For guaranteed damage she has to do b2~lasso, which you can punish by ducking the second hit and releasing bats. There's an option select Batman can use by blocking b2, ducking after and mashing on 4. If WoWo does b23 then your bats won't come out, but if she does b2~lasso then they will and you'll get a combo.
Second, slide isn't as bad as you think it is. It serves its purpose of making WoWo guess after knocking you down. It's negative on hit but that doesn't matter because she gets no guaranteed pressure or punish. It also isn't fully invincible but it cannot be stuffed easily. If it happens it's really just luck.
Third, you can punish a perfectly done iaDG if you have 3 bats and block it standing. If it's done at about chest height you can punish it with 2. If the Wonder Woman player is on point then that won't come up very often but it's good to know.
Lastly, pretty much all of her mid-screen setups involving OTGs are gimmicky and beaten by holding back + tech roll. The OTG will still work but you'll be out of range for her 50/50. Cross-up f3 can be blocked on reaction once you're used to it because it never hits in front. In the corner if you see her jump forward then the divepunch will hit as a cross-up and if she jumps straight up it will hit in front. You'll get hit by stuff sometimes but it's possible to get good at blocking it most of the time.
Edit: If she jumps forward and does the divepunch as soon as possible it will still hit in front.