I'd rather not see Kid showing up for the final showdown, I didn't really like how he kinda "interfered" with the mystery train case...so yeah, I do hope it won't be the same thing with the final showdown since Kid isn't even a "DC character" in the first place (even though he's becoming more and more involved in it). Like MacGuffin said, it's okay if he shows up before but the final showdown should only have the main - main characters, in my opinion.