For the four-week event miniseries, the supergroup will find itself split into four teams, each with their own separate rosters and themes, personally designed by Brainiac. Along with some surprising villains, joining these new teams will be four members of the current Teen Titans. Raven will be on Team Wonder alongside Wonder Woman and Zatanna; Starfire on Team Mystery with Superman and Starro (no, really); Beast Boy on Team Entropy with Batman and Deathstroke; and Damian Wayne's Robin on Team Wisdom with Cyborg and The Atom.
Raven and Starfire's inclusion into these new Justice League teams makes some degree of sense; Raven is the daughter of a demon, along with being a powerful sorceress, so it stands to reason she could learn (or possibly teach) a thing or two from Zatanna or Etrigan. Starfire is practically an adult herself -- her age is never given, but she's definitely the oldest of the Titans -- and the makeup of Team Mystery is composed of aliens that the public is either fully aware of, as is the case with Superman and Martian Manhunter, or have a vague idea of who they are, hence Starro and Sinestro. Of the Titans involved, the female members have an air of maturity about them that makes their ages irrelevant -- the real outliers here are Beast Boy and Robin. It begs the question, then, of why someone with a high intellect such as Brainiac would pick two teenagers -- a comic relief shapeshifter and impetuous, control freak sidekick -- to join up with other heroes in an effort to save the world.
The son of Batman has followed an interesting path to trying to be a hero like his father, from recruiting a team of his own to making nice with his new Kryptonian best friend, Superboy. He has the benefit of having worked with the League back when he temporarily had superpowers, but he also has a tendency to grate on people real fast. Even though he's been on a team for a few years now, he still has trouble playing well with others; don't forget that he assembled his three brothers and declared that he'd beat them up and rob them just to prove himself. Despite the genuine efforts that he's made to reform, there's still clearly a darkness within him. After all, the "Super Sons of Tomorrow" crossover hinted that whatever led to an adult Jon Kent killing millions was done to stop whatever the older Damian was doing. Can the Justice League really trust someone whose future is murkier than even theirs? Through different continuities over the years, Damian's identity crisis has been constantly explored, and it usually culminates with him becoming brutal or completely evil.