This is my first time doing this so this won't be perfect.
Disclaimer: I own nothing in Gundam or Code Geass obviously.
Prologue
Somewhere on the moon stood several giant, humanoid machines called mobile suits. Some of which are known as the famous type called Gundams. A group of mobile suits are facing a lone Gundam with armor like that of a knight, a shield, and a sword. Said group consisted of Amuro Ray, Banagher Links, Setsuna F. Seiei, Char Aznable, Ribbons Almark, and Full Frontal.
"Very good, it seemed that humanity has gained a new power, one that could end all wars." Knight Gundam stated. "With this power, I want you to use it to end the evil in another world very similar, yet different to yours."
"What? You mean you have still haven't finished your business with us?" questioned Amuro.
"Believe me. This evil very much a real threat to the world it inhabits and must be stopped if the humans of this world is to attain peace that is long due."
"Why do we have to do your dirty work for you after dragging us across dimensions and pitting us up against each other? We could have killed ourselves were if it not to agreeing to a truce to fight you." Char demanded.
"Because this evil is unjust like the ones you have fought to exterminate in your respective dimensions. An empire is oppressing nations and their people because of an emperor's hopeless view of attaining peace for humanity through the wrong method that would destroy what we would could our humanity." Knight Gundam answered. "I will explain the recent history of the world I am sending you and the others and the reason you must stop this threat."
He told them of the Holy Britannian Empire and how it formed. The human pilots were enraged by their recent atrocities they committed because of their current emperor, Charles zi Britannia. The Sword of Akasha, Thought Elevators, Ragnarok Connection, and Geass Directorate were all revealed to them. Ribbons was particularly disgusted that humans could be so arrogant, believing that they could kill Gods. The pilots learned of a power called Geass that very few humans possessed and the dangers it pose to the users and their victims.
"Now you see why I have called you all here to this world that I have used to test you all. You have all come to an understanding among yourselves, despite your different views and the worlds that you lived in. You can bring peace to this world with your powers." said Knight Gundam.
"Though it is not my world, I am Gundam Meister of Celestial Being whose job is to eradicate wars. I will go." stated Setsuna.
"If you're going then, then I will come too. I can't let you get the original Gn Drives get damaged after all." Ribbons replied.
"I can't just stand by and let others get hurt if I can stop it." Banagher said with resolve in his voice.
"This Britannia is no different from what I have fought against all my life." Char spat with disgust clear.
"I'm with Char on this one. No one has the right to assume superiority on others." Full Frontal replied.
Knight Gundam raised his word and a white light flashed before a vortex formed consuming everyone that was near the moon. "We are now in the world of Geass which you can now see for yourself. I am leaving you and the other pilots with the Celestial Being spaceship that houses what two of you know as Veda. Farewell, we will meet again when you have completed my objective for you all."
Knight Gundam raised his sword again and a white light in space appeared and disappeared along with Knight Gundam. The six pilots left to gather the others and explain their current situation with Celestial Being.
Pilots/Mobile Suit
Note: I'll add or remove characters if enough people asked enough.
Gundam 00
Setsuna F. Seiei/00 Raiser
Lockon Stratos/Cherudim Gundam
Allelujah Haptism/ Arios Gundam
Tieria Erder/ Seravee Gundam
Ribbons Almark/Reborns Gundam
Grahm Aker/Susanowo
Gundam Seed
Kira Yamato/Strike Freedom
Athrun Zala/ Infinite Justice
Shinn Asuka/Destiny Gundam
Mwu La Flaga/Akatsuki Gundam
Gundam Wing
Heero Yuy/Wing Gundam Zero
Duo Maxwell/Gundam Deathscythe Hell
Trowa Barton/Gundam Heavy Arms Kai
Chang Wufei/Altron Gundam
Quatre Rabera Winner/Gundam Sandrock Kai
Treize Kushrenada/Tallgeese II
Milliardo Peacecraft/Gundam Epyon
Gundam U.C. Century
Amuro Ray/Nu Gundam
Char Aznable/Sazabi
Kamille Bidan/Zeta Gundam
Haman Karn/Quebley
Judau Ashta/ZZ Gundam
Banagher Links/Unicorn Gundam
Full Frontal/Sinanju
Uso Ewin/Victory 2 Gundam
Seabook Arno/F91
Elpeo Ple/Quebley Mk-II
Ple Two/Quebley Mk-II
G Gundam
Domon Kasshu/God Gundam
Master Asia/Master Gundam
Kyoji Kasshu/Devil Gundam or Spiegel Gundam(I'll decide later)
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