Oh I donno. Entry-level Sharingan means you can copy damned near anything, Mangekyou brings you to a world of the originator's creations, so why not the mako-enhanced one making them unable to get caught in a Genjutsu at all because they can literally see right through it?
Zack would totally act as an older brother. It's practically in his genes.
Hah. Kakashi's crush would be an open secrete, everybody BUT Cloud would know about it. Because Cloud's oblivious like that, and would likely assume that only the girls could/would crush on him. Zack would do everything possible to protect that "innocence". *snickers* And Aerith. Oh god, she'd be such a little perv of a kunoichi. And totally be a medic-nin.