I can't find Zack & Cloud battle theme VS Sephiroth in Final Fantasy VII Rebirth anywhere, so here I make one.
Zack, Cloud VS Sephiroth fight actually starts in 04:40
Actual track bgm name in Japanese: 人のソルジャー (FF7 Rebirth OST Ver.) with a bit addition of Reunion World (Japanese track bgm name: .リユニオンする世界 (FF7 Rebirth OST Ver.))

Its one of my fave battle theme, the "Honor" in this music is so thick. Zack & Cloud reunion is very satisfying, too bad its so short.

Other FFVII Rebirth and OG OST here    • FFVII Rebirth, OG OST