Hey, have you considered doing a G.I. Joe/Code Geass crossover which takes place after R3, since you introduced Duke. Great story!

As much as I love the idea, you NEED to space this out! D: I can't even keep track of what's happening most of the time. Speech for different characters have SEPERATE lines!

I forget this characters Devcon(dotm), Reedman(rotf), Sunstorm(animated), Swindle(animated), Carly Spencer, Charlotte Mearing and Dylan Gould.

And returning characters from the first two transformers geass

Autobots: Optimus Prime(with trailer and flight gear), Ironhide, Prowl, Grimlock, Jetfire, Bumblebee(with stealth force), Jazz, Silverbolt, Ratchet, Sideswipe(with stealth force), Skids, Mudflap, Sludge, Arcee, Chromia, Flareup, Wheelie, Elita-1, Wheeljack(dotm), Trailbreaker, Hound, Inferno, Jolt and Hot Shot.

Decepticons: Megatron(dotm), Starscream, Soundwave(dotm), Shockwave, Thundercracker, Brawl, Ravage, Long Haul, Thrust, Scalpel and Scourge(rid).

People: Emperor Lelouch vi Britannia, Empress Kallen vi Britannia, Suzaku Kururugi, C.C., Nunnally vi Britannia, Rolo vi Britannia, Cornelia li Britannia( or Guilford), Euphemia Kururugi, Gino Weinberg, Anya Alstreim, Milly Ashford( or -Cardemonde), Rivalz Cardemonde( or Ashford-), Nina Einstein( or Simmons), Spike Simmons, Shirley Fenette( or Lennox), Josh Fenette, Sayoko Shinozaki, Kaname Ohgi, Yoshitaka Minami, Kent Sugiyama, Shinichiro Tamaki, Kyoshiro Tohdoh, Nagisa Chiba, Rakshata Chawla, Ayame Futaba, Ichijiku Hinata, Mutsuki Minase, Jeremiah Gottwald, Villetta Nu( or Ohgi), Gilbert G.P. Guilford, Cecile Croomy, Sam Witwicky, Robert Epps, Graham, Empress Tianzi, Li Xingke, Hong Gu, Zhou Xianglin and Naomi Kozuki.

I know the forth series is set between R2 and R3

And also you should this characters in Transformers Geass RX(some of them are from R3)

Autobots: The Wreckers(Drift, Mirage(dotm), Nightbeat(base on Prowl from Animated), Leadfoot, Roadbuster and Topspin), Brains(dotm), Bluestreak(g1), Smokescreen(g1), Brawn(g1), Powergilde(g1), Sea Spray(g1), Snarl(g1), Slug(foc), Swoop(g1), Skyfire(base on Jetfire from rotf), Perceptor(g1), Sentinal Trion(base on Sentinal Prime from dotm), Ultra Magnus(animated), Wing Saber(cybertron) and Evac(cybertron).

Decepticons:Dirge(g1), The Dreads(Crankcase, Crowbar and Hatchet), Laserbeak(dotm), Igor(dotm), Driller(dotm), Insecticons(prime), Dreadwing(prime), Skyquake(prime), Rumble(g1), Vehicons(prime), Obsidian(bm), Strika(bm), Airachnid(prime), Breakdown(prime) and Knock Out(prime).

You should put elements from Transformers Dark of the moon and Transformers Prime.

Hot rod and Nunnally are a great pair

which Blitzwing is in this fic G1 or animated

Please write a brand new transformers and geass crossover fanfic, and add some more stuff from the transformers multiverse would you please.