Nova (a possible idea)- a huge fanfiction

Hello, all, and thanks for the help.
I'd like to begin an SB where loads of different characters from all different types of fiction (TV, anime, books, movies- with my approval, of course) come together to fight a supreme evil.
But I'd need a plausible excuse for them to meet and decide on a technological era.
So help would be appreciated

I still like my suggestions...

Your suggestions were cool Do remind me what they were, though. And what about the tech age?

My suggestion was that time and space was ripping itself a part and that different dimensions are merging. They eventually create one big dimension. So there we have it. We have a problem. Characters. It's all good