The Dark Knights is the answer to the very weird question: What if the Justice League was evil, and everyone was Batman? Each member is pulled from an ugly corner of a dark universe, each member is an analogue of a classic Justice League character, and each member is Bruce Wayne. I guess when there is an infinite multiverse to browse you can check off whatever boxes you want. Why not a quartet of teenage ninja turtle Batmen? Membership eventually opens up to multiversal villains related to Bruce Wayne, just to keep it creepy.
References: [dc.fandom.com: Dark Knights]
[dc.fandom.com: The Pearl]
[org]
Metahuman Database 