There are a few villains in the DC universe where those who fight against each other will put their differences aside because they are deemed the bigger threat. Darkseid is one, who will be available as a pre-order bonus for Injustice 2. The other is Braniac and in this fifth Shattered Alliances trailer for Injustice 2, you can see a hint at what will bring two of DC's biggests heroes together, albeit briefly most likely.
Braniac has long been one of the biggest villains of Superman. He's also one of the most powerful villains in the DC universe who only cares for himself and the collection of data while destroying anything in his way. The game has him in his classic green form with mechanical tentacles to aid him when he fights.
Injustice 2 will be out for the Xbox One and PlayStation 4 on May 16th.