I am surprised that there isn't an article on this topic yet, so I am just gonna go ahead and write an article on it now, and trust me when I say I have been following every single bit of information on Batman vs Superman Dawn of Justice right from July 2013 and I have been reading every single rumor, alleged (fake) leaks, posts, insider scoops, interviews, press notes, set pictures, videos and whatnot about this movie and when I take a look at those from a macro level they kinda form an intersecting pattern and with that perspective of mine let me take a shot at this and guess what, this is purely an educated and logical speculation from my side based on every bit of information I have ever read on this movie, it may or may not happen but chances are that it might happen.
We are already introduced to Superman and almost everyone who is reading this article would know how they would get introduced to the new version of Batman played by Ben Affleck, so let's discuss about the other Justice League members starting from......
Well I believe that Wonder Woman is gonna have an important supporting role in this movie but with a screen time of something between 15-20 minutes, and she will be introduced to us as a sophisticated and super rich humanitarian known as Diana living in the man's world, you might ask how do I know this, well she was spotted on the sets of Lex Luthor's party scene and she's said to be one among the invited guest to that party and I don't think anyone out of the privilege circle is going to be invited to one of Luthor's party.
But apart from that we also know that Wonder Woman is going to be some hundreds of years old in this DC Cinematic Universe and it is my understanding that Diana left Themyscira (her mystical home island) and came to man's world all those years ago to fight for woman empowerment in the early 20th century and then doing other humanitarian works and maintaining a low key in the public eye and whatever that will happen during the events of Batman vs Superman Dawn of Justice will force Diana to suit up as Wonder Woman and put those decades of warrior training to test.
Jason Momoa's King Orin is going to be a cameo at best, to get us pumped about the king of seven seas, Lex Luthor is said to be secretly running a massive scale search on meta human activity post Man of Steel and I think we would get introduced to Aquaman and maybe about the Atlantean myth as well through Luthor's activity, through a satellite video footage
It's highly likely that this movie would end with a montage on " Dawn of Justice" and in that montage we might get another look at Aquaman, so his involvement in the movie is really small, it won't be substantial and there wouldn't be a subplot dedicated to Aquaman as well.
Victor Stone (Cyborg)
Ray Fisher's Cyborg will also be a minor cameo and I think he wouldn't even become Cyborg in this movie and it is my understanding that he will be introduced to us as a top college football/rugby player who has daddy issues, saying this because Zack Snyder shot two football matches between Metropolis and Gotham and Victor plays for team Metropolis.
This sequence could be a really cool metaphoric opening sequence, shot in Watchmen opening credits style with that Metropolis vs Gotham (Superman vs Batman) vibe going on, it would be even better if Clark Kent is covering that match for Daily Planet while Bruce Wayne is seated on the VIP panel as a guest or something.
What I am trying to say here is Victor Stone will be a part of this football match sequence and maybe in another sequence where he might reflect upon the awesomeness of Superman (hero worship ?) when he catches a glance of him , I don't think there would be anything more than this for his character just a quick and clever intro to his character which can be expanded and explored more in Justice League Part 1
Well this guy he wouldn't even appear physically and by physically I mean Ezra Miller will not don the Flash suit in this movie but still there would be a cameo of Flash, it will be a CGI cameo and it will be a "red blur" across the screen and another verbal reference to Flash that goes along the lines of "there's a guy in central city who can run at sound speed" this can come from Lex Luthor as a part of his secretive search mission. Well I don't even think this is a cameo it's more like an easter egg.
Saying this because Ezra Miller was never spotted during the production of Batman vs Superman (Even Ray Fisher said he didn't meet Ezra Miller) and he never trimmed his long hair and beard to don the red suit of Flash.
Green Lantern/Hal Jordan
Well this is an interesting one because I believe he won't appear in this movie at all. Because there isn't an actor confirmed for this role yet. But I firmly believe there might be an easter egg or two referring to Hal Jordan/ Green Lantern.
Maybe something like a file under Lex Luthor's search which refers to a mysterious crash that had a glowing green object or something like photographs of emerald green blur moving across the skies of Coast City and out to the space.
Saying this because I believe Guardians of the Universe would have realized their mistake and would have sent a Green Lantern power ring to Earth after Zod's invasion and Hal Jordan would have left Earth to train in Oa with the Green Lantern Corps and he would return to Earth only during Justice League Part One.
Wrapping it up
So that's about it folks, with all the available info in my hand I believe these would be the Justice league centric cameos and easter eggs, and I have to say this is a genius way to include everyone without over stuffing this movie. So which one was your favorite let me know in the comments below.
Note: Remember that this movie is in editing process and the movie is still 9 months away, so there are chances to add or remove certain elements from the movie and maybe Flash and Green lantern can indeed appear in the movie physically or even Aquaman or Cyborg's role can be increased through re shoots, but for the most part I believe the cameos and easter eggs would be executed as stated above.