The one true shame of the Suicide Squad's film universe is that their team lineup will never, ever come close to rivalling the sheer unpredictability and diversity of the comics themselves.
Because the Suicide Squad has had some members that you couldn't predict given a hundred years and a list of every DC character ever. Not only does the series occasionally flirt with the idea of having superheroes in it, but it also uses villains seemingly too powerful to be forced into a government crack squad. After all, Task Force X are meant to be a shadowy black ops unit; throwing a hero in there is bound to raise ethical questions, while throwing in a heavy hitter doesn't really speak to covert action.
That said, it's not as though anyone is going to complain about seeing Power Girl or General Zod making a surprise appearance in a comic, so the sky is truly the limit for whoever finds themselves marshalling the Squad's next adventure.
With the series having published its first issue over thirty years ago, there are also characters in the Squad that seem like crazy choices because they are either entirely different now, or way too famous for you to ever think they'd been in the team of villains in the first place...