It's obviously no secret that Doomsday will be in the game. Obviously, he is. Though it isn't confirmed whether or not he is playable or a boss. However, I thought of something that might just confirm that he is playable.
In this image, Doomsday and Joker are fighting in the Fortress of Solitude
In the only images we've seen of Doomsday, he is fighting the Joker in the Fortress of Solitude. I can think of a few reasons why Doomsday would be in the Fortress, but why would the Joker be there? Now there is one possibility that Superman brought him there for some reason, but that's unlikely. So do you think this is good evidence of Doomsday being playable or can you think of a good reason why Joker would be in the Fortress of Solitude?