He and fellow SOLDIER Type-G Angeal have the ability to make copies, there's nothing special about the pods that were used and Zack can't become like them.
But we are talking about a
technology that got
stolen. I don't know how one could steal a physiological ability.
So
this pod would have nothing to do with Genesis's copies ?
Let me decribe the scene.
Sephiroth leads Zack to evoke copies and when it's done turns his head to look at the machine. The camera changes angle by positioning itself inside the machine and looks at Sephiroth through the porthole, a little like what a person placed inside would do. Sephiroth evokes "abominations", while staring at the window.
I find this staging quite awkward if it is not intended to make us think this machine is related to the copy process.
Cloud is a copy of Sephiroth, no one else, he also used Zack's story to forge a SOLDIER First Class identity because he himself wanted a SOLDIER First Class identity.
How did Cloud got copied form Sephiroth ?
Zack is fair and a beautiful story, Genesis however is a trainwreck, both from a narrative standpoint and on a genetic level. And that quality is important.
Genesis get its name from the story that tells a certain view of the creation of the Earth and of mankind. I guess some can find him beautiful.
The Planet is the one entity that is attacked by and suffers from the greed of humanity. That remark reminds me of this Genesis's sentence :
"If this world seeks my destruction, it goes with me." (
CC - extract)