[quote=@Silverwind Blade]
<Snipped quote by vancexentan>

No, you won't be forced to pilot GM's or Jegans. It'll be a selection of various variant versions of those, and some mass-production Gundams and other suits. I haven't nailed down the specifics yet, but there'll be a healthy selection. Part of the units' background will be that they're also operational test/evaluation for previous models of mobile suit and putting them into action, and their mecha were pulled together from the remnants and left-overs from earlier conflicts and special groups that have since disbanded.  
As I said in the opening post, I'm not going to be fretting too much over exact continuity, but for the sake of answering your question, post-Char's Counterattack but pre-Unicorn, or even alongside Unicorn, but removed from the Earth Sphere and more out in the asteroid belt/Mars/potentially even the Jovian system, leaving things free to not be too bothered by the same characters, events, etc. I will be deliberately ignoring any manga, side-stories, etc that happen in those places and times to tell my/our own story, and the same for post-CCA/UC100 continuity. 
Also it will be a group of Zeon remnants generally smooshed together, consolidating under one group for survival etc and otherwise being a nuisance in the outer Solar System. 
[/quote]

Will it be possible to avert future events/tragedies somehow, like the events of Narrative and Hathaway's Flash?