I feel like that concept alone could make a good one-shot story. Also, I think there are two different ways for this to work: A character with previous experience as a superhero being inducted into a team, or a scenario where the candidate, at least if successful, gets her powers as part of the package, in which case there would probably be a lot more training about power use, testing for compatibility, etc. Any thoughts? And now that I think about it, what about the initiation for a villain team?