Alright everyone, I'll probably have to edit this a few times because there will probably be major questions about the sentient evil energy bits, the whole "ultra cards" thing and all the scenes.
Anyway, this is my version of the Gaiden Mini-Series Crossover. It is very abbreviated, but please enjoy!
Part 1: Minus' Backstory and The Starting Point of the Multiversal Disaster
We already know about Minus' origins; they are explained on his page
Freedom and the Monster Army
Minus is trapped in a pocket dimension contained in a black hole, but is freed by a mysterious being of sentient evil energy, who gives both him a device allowing him to travel dimensions and a power boost. Minus heads for the Monster Graveyard, and revives thousands of Kaiju, but on the way he corrupt two powerful aliens into Super King Galtan and Super King Jackal. He sends the monsters to attack the Fan Ultras' homeworlds. The kaiju are distributed randomly, so, for example, some Giz and Orion monsters attack Argentium, some Gamma and One kaiju attack the Land of Ultra, and some Sorta and Draco kaiju attack the Land of Giants.
Afterwards, Minus travels to each universe, takes the main ultra's powers and seals the powers in the Ultra Cards. He leaves the Fan Ultras, now dormant inside their human hosts or forms, and calls the monsters back to his new palace on the Dark Planet.
Part 2: Society X
Minus uses his chaos powers on the Ultra Cards, and creates chaos copies of the ultras. He lets them develop, while he observes the Fan Ultras. However, soon Society X breaks loose. Minus lets them go, as he sees they will create the chaos he needs to complete his plan. He then attacks his universe's Land Of Light, and with his army and new power destroys it.
The ultras, however, are tracked down by Society X. Society X easily beats them down, and prepares to kill them, when a bunch of secondaries come assist the main ultras, who barely kill Society X, and get their powers back. However, the main ultras are teleported to the Dark Planet by Minus, where the final showdown begins...
Part 3: Minus vs. Ultras
The ultras fight Minus, but are beaten down. He then reveals his plot: to destroy 90 percent of the omniverse's lifeforms, including all ultras and all humanity, and to corrupt the remaining 10 percent, all with his collected chaos energy. The ultras manage to destroy Galtan and Jackal after a tough fight. Chimera, Wildcat, Gaixus, Diana and Kain show up, but they stand no chance. Even in their ultimate forms, the ultras are beaten pretty hard (Draco and Reuz are smashed several miles through the planet, Moedari and Element are hit halfway across the universe, and Zach and Giz are smashed into a nearby meteor at supersonic speeds). The legendary ultras show up, but they are beaten hard, although not as hard as the main ultras.
The ultras use a combo beam to destroy Minus' Dark Palace, but the collected Chaos energy stored in the castle is absorbed by Minus, who enters his Evo Mode, and splits the planet in half. He launches the ultras to earth with a dark beam, and they land on an artifical landmass (manmade island) so hard that they fuse its surface into glass, and are reverted to human form. Minus lands, and prepares to destroy earth by dissolving every particle on earth by coating it with Minus Energy in strong enough concentrations to dissolve positive particles...
However, even in the face of destruction, the inner light of all life on earth revives the ultras, who transform directly into their ultimate forms and evolve into glitter versions. Minus is shocked to have been hurt by a slash attack, and all the legendary and most of the secondary ultras (who had turned into statues) are unsealed by the light. Minus is eventually destroyed by all the ultras' finishers, with Orion delivering the finishing blow.
The ultras are seen in human forms on earth, at a resturant, celebrating their victory, before returning to their universes.
Orion: Main Ultra
Lunaram: Secondary/Legendary (Regina Mode)
Lugeno: Legendary (Sacred Form)
I hope this is a nice script.