@Theyra Hmm, i know Bruce and Sep already said they are trying to keep away from defunct timelines and alternate universes for the moment as this is still the very dawn of the Superhero age. But i think characters who have time travel as part of their backstory (Like Booster Gold and Bishop) might be alright. Worst the GMs can say is... Well, honestly the absolute worst they can say is "Get the fuck out, you're banned" but that's not likely.