The film was mentioned that both Superman and Batman will be fighting each other like they did in Dark Knight Returns comic book adaption which is likely to express a contrast on how the heroes handle public threat situations
Now for the cast that is returning for the sequel
Henry Cavill will be back on set as Superman
Amy Adams as the red head Lois Lane
Laurence Fishburne as Perry White
Diane Lane as Martha Kent
Other cast members of the first movie that are available:
Harry Lennix as General Swanwick; since Snyder invited Lennix to recite the bold quotes from the Dark Knight Returns comic adaption, he'll be back to resume his military law enforcement role in the DC Cinematic Universe
Michael Kelly and Rebecca Buller as Steve Lombard and Jenny; two fellow co workers at the Daily Planet with Lois Lane and Clark Kent. It may seem unlikely but they will be back too since they are both still alive.
For the actors that maybe returning regardless of the events from Man of Steel
Russell Crowe to reprise his role as Jor-El (holographic figure that serves as the character's artificial consciousness); may seem unlikely but it may since the ancient scout ship was one of the only Kryptonian instruments that are still present on earth, Snyder will have everything planned out soon
and
Kevin Cosner as Johnathan Kent (through flashbacks)
Now for some of the Batman characters set to appear in this film
Ben Affleck is set to play Batman
Guy Pearce is speculated to be the next Commissioner Gordon
John Cleese as Alfred Pennyworth
Brooklyn Decker as Vicki Vale
Now before Zack Snyder starts filming, he needs to include certain villains of both Superman and Batman for the movie and these are the best choices for him to use
Lex Luthor
Stephen Lang as Black Mask
James Badge Dale to arm himself up as Deadshot
Matt Gerald as Metallo
Ray Stevenson as Killer Croc
Jason Momoa as Bane
and
Doomsday