You look nothing like Christopher Lee:ninja:
I don't think they're bothering with Green Lantern for obvious reasons. Shazam would make some sense I guess to have around so Wally isn't the the sole child member of the group.
You could also use Martian Manhunter like the cartoon.
Um, movie Flash is Barry, not Wally. And I know about the GL shaming lol, but they do have a GL Corps movie in 2020, I believe.
I thought of Martian Manhunter too, but didn't David Goyer insult the fans by literally claiming that nobody has heard of Martian Manhunter? He obviously doesn't speak for everyone and plans could change, but that was pretty telling. Especially with how DC Comics seems insistent on not having MM on the main JL team in the New 52 for some reason.