The gackt boss version in all there of it's phase armor and type Leo's three different phase form. Since well, they are original units after all....and they have a series on their own which kind of mimic the generation system.
Well i don't think that extreme gundam will make it. Extreme gundam is a figurehead for Gundam extreme vs and Overworld needs more refined moves instead of copying the same moves over and over again. --- Currently Playing: Unchained Blade
most of the "game" mechs have some backing in one of the gundam timelines, the same can't be said of the extreme gundam and the musha gundams. --- Claims List is in quote."Let's just take it easy and agree to disagree when it's debatable, not when facts are involved.." - Me
^Yes, they appeared when their series was listed. They're not in this one.
But as for Extreme Gundam, the very last series is "other Gundam games", so technically they can have any unit from any game they want even if its series is not listed. But obviously this doesn't mean to get your hopes up and it's just for the odd couple of additions.
One thing I can tell you that will be in that category is Lost War Chronicles.