One of the DC Cinematic Universe’s major problems is they are being accused of just ripping off the Marvel’s plan, and the reason is they are right. They are introducing Superheroes with the goal of the big team up and putting the focus on becoming a superhero. They can d something completely different by focusing on an evil Justice League and make the theme be staying a hero.
The villains should be the Crime Syndicate of Earth 3. In Earth 3 the heroes are now the villains with an evil Superman, Ultraman, and an evil Batman, Owlman, as the most famous. Ultraman to counter Superman’s humility is a tyrant. Like Superman he is normally portrayed as redeemable with good in him, but he is villainous. He wants to rule Superman’s dimension as well as his own. Owlman is a complete monster. He saw the multiverse and decided the only choice that matters is to destroy everything.
One problem of having so many heroes and villains is the time to develop them. With most characters having a counterpart every action will also develop their counterpart. When Superman has problems with the corruption f powers it will also develop how Ultraman faced the same temptations with the difference being Superman was not overcome but Ultraman was.
The next sis that a major villain can only last so long. Eventually the Earth 3 villains will realize Owlman’s evil plan. They will be redeemed by their counterparts. Owlman’s plan will not work and things will look good on Earth 3, but not on Earth 2. They will realize the Justice League in a world so like their own a Justice League so like their own faced challenges so like their own and turned evil. Are their heroes destined to turn into their enemies. Cadmus, Checkmate, and Suicide Squad come to check the Justice League’s power. Theywill oppose a tyranny and ironically become tyrannical themselves. Te Justice league will face the exact same challenge of their counterpats and try to not become corrupt with power like they did.