[quote=@LeeRoy]
Tifa can beat a godlike being to death, the two just aren't comparable.
[/quote]

You mean she tags along while Cloud and the more powerful teammates do the work; she did literally nothing in the Bahamut fight and probably similarly in the fight with Sephiroth at the end of the game. In a literal sense, she probably did quite a bit in the boss fights throughout the game, but only with the crisp teamwork of her allies, which wouldn't be restricted by a battle system or a trio-party-system the game enforces.