You can only fight the Enigmatic Soldier and Enigmatic Man in the FM versions of KH1 and KH2. And the hardest mode is Critical.I Freaking LOVE that remix.
i have it as my favorites on youtube.
mann the boss better be a challenge.
because all the secrets boss were cake, for me in the past kh games and i had them all on proud mode.
Sepheroith doesn't count. Unless you actually mean the above stated.