Quote Originally Posted by Endless Twilight and Gamefaqs
Safer*Sephiroth's stats change depending on various factors:
+30,000 Max HP, 2 Att, 20 Def, 5 MAt, 16 MDf per character at L99
+80,000 Max HP if you cast Knights of Round on Jenova*SYNTHESIS


You can lower Safer's max HP by 100 every time you kill Bizarro's Head. This can be done repeatedly to remove up to 24,900 HP.
There.

And you still aren't answering the question. Is there any proof those characters were at level 99? Otherwise, and assuming they didn't use KOR on JENOVA-Synthesis, he would have his normal HP. And, like I said, I've done the same thing before. Shee...

Add-on: Once you have a mastered copy of every magic materia, go to the Huge Materia in Bugenhagen's observatory and examine the Huge Magic Materia. (I don't remember the color of all the materias though. )