I have beaten all the ones I own.

FF1 on easy.
FF2 on easy.
FF4 everything done except for the summonings you get from guys like Imps and haven't got Cleaver.
FF5 everything done excepr for beating Omega and Shiryu.
FF6 everything done.
FF7
FF8 everything done except for beating Atom-092.
FF9 everything done except for beating Ozma.
FF10