Bravely Default Nemesis Strategy: Level 80 Belphegor

Finally defeated this one, and it took a pretty specific party build for me to do so.  So here I am, being a bro, sharing that party build.

Party:

• 2x Quick Performer: Thief/Performer, Support Abilities:
• Speed 30% Up
• Speed 10% Up (if you have all five slots, take Speed 20% Up instead, we want these guys to go first)
• Support Healer: Spiritmaster/White Mage, Support Abilities:
• BP Limit Up
• Magic Critical
• Holy One
• Damage Dealer: Vampire/Swordmaster, Support Abilities:
• Monster Ability Up
• Magic Critical
• Critical Amp

Equipment:

• Boost INT on the Damage Dealer
• Boost MND on the Support Healer
• Boost AGI on the Quick Performers

Turn Flow:

• The Quick Performers will always use My Hero.
• The Support Healer will use:
• Group-cast Curada in most cases
• Fairy's Aid on the Damage Dealer whenever its effect runs out
• Enigma when Belphegor uses Sloth to put all the elemental weaknesses on the party
• Stillness if you need to panic heal or resurrect, and repeatedly until you recover fully
• The Damage Dealer will use Free Lunch followed by two of Firaja, Blizzaja, and Thundaja according to Belphegor's sequence, and then next turn use the full sequence.  The sequence is the same as the level 20 version.  If the damage dealer ever has 3 BP, they can do the entire sequence on the turn where they use Free Lunch.

If you don't have Firaja, Blizzaja, and Thundaja:

• Use My Hero on the Quick Performers just like normal.
• Use Stillness on the Support Healer until Belphegor's used all three of them on you, so that Genome Drain can give them to you.  Then wait for Stillness to wear off and begin attacking.
• Default on the Damage Dealer until you have all three spells and Stillness has worn off.

How it works:

• My Hero gives the entire party one BP per use, including the Quick Performers.  Two uses of this combined with the normal BP gain at the end of every turn means you can use 3 BP per turn, every turn.  My Hero is thus spammable, and your Damage Dealer can Brave twice on every turn.
• The Support Healer boosts your damage output and reduces the damage you take, as well as healing the party.  Since you'll be swimming in BP from the performers, that extra BP from the BP Limit Up support ability only serves to increase your flexibility and ability to recover from whatever Belphegor just did, and make it easier to resume your normal rhythm.  In my fight, my healer took their turn just after Belphegor, which made queuing up a group-cast Curada while the party was still at full health quite effective at keeping everyone topped off, with minimal MP waste.
• Since the Damage Dealer uses Free Lunch, the high MP cost of Firaja, Blizzaja, and Thundaja is nullified entirely.
• You can just ignore the spheres that Belphegor summons.  You'll hit their weaknesses eventually, and they die pretty quickly.  By the way, if you've used Examine on the level 20 version of Belphegor, you won't have to Examine this version to be able to see its weakness.  Take advantage of this.

I imagine that this party build would work pretty well pretty much anywhere in the game, especially on other nemesis fights.  It might not bring enough damage for some situations, though, so be mindful of what you're up against.  Dedicating two party members to BP definitely lowers potential damage output, but in this case, it makes the entire build work.