I honestly think that the story to my main MUGEN game is like this:
Chaos and turmoil is spreading throughout the vast multiverse and the time-space continuum. So, Goku, Shana, Kamen Rider Decade, and Kamen Rider Zi-O are sent to fix it. Along their journey, they meet many friends, foes, and anti-heroes that cross paths with (and sometimes, join) them while at the same time trying to figure out who's causing all the problems and distortions the many universes are facing.