Ultra DC is a universe where many, many things have been changed, though a few things remain.
Thomas Wayne, Jr. was a wealthy buisnessman who owned a famous company, Wayne Enterprises. However, he realized his ego and love for his company had gotten out of hand when he missed his mother and father's funeral. After this, he swore to make it up to them by becoming the Batman.
In an alternate universe where humanity focussed more on science than anything else, a man named Jor'l was mocked and made fun of for claiming their world was going to blow up. Because of this, just before the planet did blow up, Jor'l launched his son, Kal'l, to another world, where he was adopted by the Kent family, who renamed him Clark.
Ultra Wonder Woman
Years ago, there was a great war between the mighty Amazons and the ruthless Cheetah Clan. Eventually, they would wipe each other out, with the final two warriors, Diana and Priscilla, would die in battle with each other. Years later, Diana was reincarnated in the form of Diana Prince, who, when she found out about this, became the Wonder Woman.
Ultra Green Lantern
Years ago, the Guardians of the Universe came to Earth and experimented on Neanderthals. In the modern day, the Guardians returned to Earth, explaining the experiments left untapped power in everyone on Earth, and that they have done this to other world. They said they would chose one human to have their power unlocked, and that human was Hal Jordan.
Barry Allen is a famous scientist who began work on proving alternate universes exist. He was called crazy for this, but eventually, he proved everyone wrong, as he opened a portal to another world. He stepped through, and was struck by strange lightning before being thrown back through the portal. Barry shut the portal down and found out the lightning gave him super human speed, he now protects his city as the Flash.
The heroes of the world come together to battle giant, world ending threats that they could never imagine fighting alone. They battle threats that range from powerful humans to aliens form other world. They are the Ultra League, and they are here to stop all the villains around the world.