It's Kinda Complicated ... Well, from what I can tell, Ultra Galxy takes place in the far future when humans have settlements on other planets, and when Ultraman, Ultraseven and Mebius show up in the Ultra Galaxy movie, their human forms don't seem to have aged much. So I guess, what ever way is convenient for the movie they're doing, or something like that.
Another thing I'm wondering, since Mebius had his Crew GUYS uniform in the 8 Brothers movie, it should mean that he goes into that universe not too long after the Mebius series. Which means that he would've met the AU Dyna/Asuka very long (probably centuries) before he met the "proper" Dyna in Ultra Galaxy. Which would mean that AU Daigo and Asuka from Super 8 Bros. are chronologically the "originals", if chronology was linear when you cross dimensions.
Um, did that last paragraph make any sense?
It did. But, best to think of the Super 8 UltraBrothers Alternative Universe as a totally separate universe, apart from the standard Showa and Heisei Universes. Keep in mind that, the Super 8 AU was set in 1996, whereas in the Earth One Universe of Tiga and Dyna, Tiga took place in 2007, and Dyna took place in 2017. In the Earth Two Universe of Gaia (& Agul), that took place in 1997, which makes it pretty contemporary to Super 8, however, Earth Two is far more technologically-advanced, mainly due to the Alchemy Stars. Probably, the "dreams" from the real Heisei AU's were being drawn back in time to the Super 8 AU.
Probably what happened was that whatever force had secreted the human hosts (as well as Ultra Seven in human form), and their significant others, in the Super 8 AU had deliberately chosen a time period that they would all be comfortable in, in order to live a safe, happy retirement from action, undisturbed by the traumatic memories of their previous lives. But, as a fail-safe, they retained access to their powers, and would just need to be "re-awakened" if danger showed up. At least, that's
my pet theory.
More realistically, though, what probably happened with Asuka is that, when he was yanked thru the GranSphere's final black hole at the end of Dyna, he not only went into the Showa Universe, but also into it's far future. Since Ultras can live for
thousands of years, Mebius probably hasn't aged much at all.
