Eh I just beat it not too long ago. Level 50-54 all characters, not even full board filled up. Best equipment was the stuff bought from shops, well minus a peice of Maximillian for Basch. But over all Ididn't really have a lot of the strongest gear, and I still won pretty easily. Just needed my good 'ole Cura/Curaja spam every now and then. Honestly the hallways before the final boss were tougher then the fight itself in my opinion. >.>

But yeah, no worries if you don't do everything before hand, you could just go and beat it and see the ending then go back to do all the extra stuff later like I did.

Anywho's good luck and enjoy the ending. ^^b