I've divided series into Past, Present, and Future, and listed the series that are active residents in our present while describing the world the Gran Knights are there more to round out the roster
Buddy Complex drags our good friend Watase Aoba to our time from the distant past, lots of timey-wimey nonsense involved, but other things are moving forward with him. It isn't noticeable at first, no one else shows up where he does, but the already crowded Byston Well is starting to swell up
Operation Meteor, the resulting war to end all wars lol, the True Operation Meteor and dissolution of the Barton Foundation at the hands of the Gundam Pilots
Heero Yui has tried to take down Hayato Jin during the terrorist's time before becoming a Getter Pilot, and the team as a whole have had to work around the three other groups.
Wings of Rean: Aesop awakens to a Byston Well he doesn't recognize, with only Elebos as his guide and the Nanajin to be his sword. Luxe and Shinjiro Sakomizu are enjoying the hospitality of Bishott Hatt, who is also hosting Luuza and Rimel of the House of Luft.
Gundam Wing Endless Waltz: Relena Darlian finds herself in the custody of the supposedly missing Paptimus Scirocco in Byston Well, observing as he navigates the local polities while searching for a way back to the surface. At her side are Lucrezia and Zechs. Meanwhile, the pilots find themselves scattered across the Earth Sphere-
Trowa and Wufei are thrust deep into Zogilia territory, offering their services to the army to gain perspecitve on this new planet. Duo is over in France, working with Chasseur and the GGG detachment there against Bio-net, while Quatre and Heero stay with the Heim family in rural Ameria
New Getter Robo: The Getter Team find themselves at a decrepit shell of the Saotome Research Institute, playing guard duty for a Professor that shares a name with their own against an enemy they've never encountered before.
Mazinkaiser SKL: The Kaiser is buried in the Mountain Cycles near Paradigm City. Kaido and Magami don't have the tools to get it out, so they rent themselves out as bodyguards to Roger Smith while Tsubasa seeks out the necessary crew to retrieve it
Dancouga Nova: the entire Dragon's Hive is sitting underneath Castle St. Germain, and F.S. has managed to strike a rapport with Sandman. Team-D is working to support the Gran Knights while they investigate the phenomenon that brought them here
Protagonist A: Eleanora "Ellie" Rosencroft is, despite her relative age, one of many amnesiacs from Paradigm City. Like many of the much older residents, she has moved away from the domes to the country-side, where she pilots a biplane for the Militia. On occasion, she does some investigative work from the skies for Roger Smith.
She doesn't know much of herself from before she awoke in the city, but what she does know is the inner workings of a giant transforming robot that she supposedly has yet to see in person.
She learned to fly alongside Sochie Heim and Beltorchika Irma, and has personally slapped Roy Focker off a chair, who proceeded to laugh it off before bonding over flying planes
the Gran Knights are there more to round out the rosterthat's not getting into the people that managed to stick around the old-fashioned way, certain Machina Factors and Sandmanlol, the True Operation Meteor and dissolution of the Barton Foundation at the hands of the Gundam Pilotsthe mystery thickens as Aesop met Aoba and Hina both when they were already in college, so them being high-schoolers throws him offsupposedlyhas yet to see in person.