They've had Flash, Green Arrow, the Legends of Tomorrow, and of course Superman cross over with Supergirl; but I don't read any of those in comic books and don't even read Supergirl; and it would be nice to have Green Lantern make an appearance. That would be something that would be cool to see. She sees green strange stuff, but it does weaken her like kryptonite does.
Take care and God bless