Exploration: Royal Road

Lupis and Yew will fly into the air on Kain's back to dodge it (and the other two presumably following) while Mr. Fuzz will summon Stock Mecha Knight and hang onto his claw (SMK has a scorpionlike tail with a claw on the end that stays attached to his head when not in use) as he takes to the sky.

Since Yew didn't actually do anything last turn other than ride Kain he should have an extra BP, so use it to cast Fire Mirror Blast. Fly back down to the ground at let the exploding rocks and fire breath be reflected right back at Pyribbit.

Wait, if I had Fire Mirror on everyone then how did the fire breath hit them? You caught that I said Fire Mirror Blast, right?
Anyways, Yew heals himself with Curaga, Lupis uses Body Shield, and Mr. Fuzz summons Whispy Woods to blow away the smoke (on a side note, you have no idea how tempted I was to use Whispy last fight and have a tree battle) before sending out both Poliwhirls to use Hydro Pump and Paula and Gogo to use PSI Freeze Omega, hopefully freezing any residual water as well.

That works. It also doesn't really change my next move, but at least it means that nobody else is injured.

Whispy returns to the sphere, but the two Poliwhirls, the psychic girl from Twoson, and the famed Mimic all perform their attacks from last turn (Hydro Pump from the Pokemon, PSI Freeze Omega from Paula and Gogo) aimed higher up at Pyribbit while Mr. Fuzz holds him down with Chaos Control.
"Die already, you stupid frog! THIS IS WHY NOBODY LIKES YOU!"

(Roughly how many more are we talking?)

(Hmm... Honestly, without the ability to use a Miracle Fruit the final phase may very well be worse than Soul of Sectonia, so let's do it.)
Summon everyone in the sphere. Giant Mettaur will hide under its helmet, acting as an invincible wall (seriously, none of the enemies here have an attack that could even damage a normal Met hiding under its helmet, much less a giant one) for the party that Yew will send all single target attacks aimed at the party to with Kairai. Xernias will stand behind Mettaur and power up with Geomancy before unleashing hell with a barrage of Moonblasts. The Poliwhirls will spam Hydro Pump. Whispy will attack with roots erupting from the ground under enemies. Gogo will use Mimic as often as possible, at which point whoever's actions he mimics from my party is going to be pretty random. The random Esper... I need to know which one it is first. Shieldon will spam Swagger so that the enemies murder each other or even themselves (and if any attacks do come our way, they're redirected at Mettaur anyways). Paula will attack entire rows at once with PSI Fire Omega. Cactuar will dribble around the party, casting Haste on everyone to let them get off even more attacks. Rush will use Rush Medic, flying around in the air while dropping health pellets as necessary. Mettaton will keep his back against Mettaur so nobody can flip his switch (and thus he stays in his invincible first form) and attacks the souls of his enemies directly. The R.O.B. Units will shoot lasers at enemies and use Robo Spins (or whatever their side B is called) on any foe who gets close. Agnes will use Meteor, casting at a steady pace to not run out of BP and using Curaga or Arise whenever someone urgently needs medical attention. The Baby Golden Chocobo will use Choco Comet. Gamma will sweep his sights about the area, locking him to large groups of enemies to unleash massive comboes. Pikachu Libre will use Flying Press and Thunder. The bunny's attacks can be summed up in two words: Monty Python. Without the Masamune to Octaslash with, Sephiroth will stick to Shadow Flares. Stock Meta Knight will take to the air, shooting lasers from its eye, missiles from its wings, and grabbing corpses and throwing them at other enemies with its claw. Nightmare (orb form) will fly around erratically while shooting stars. Guitarist Pichu will play the Song of Storms to boost the Polis attacks and increase Thunder's accuracy to 100% for both Pikachu Libre and itself. Lupis will use Multi Attack, darting about and striking at all enemies from Kain's back. Finally, Mr. Fuzz... To be honest, I think I'm busy enough directing all of these attacks, not to mention that I don't really need to do anything since I've got an army unleashing a barrage of attacks while completely safe from retaliation (and if somehow Giant Mettaur does get KOed, I've got contingency plans keeping everyone alive)
Edit: On second thought, rather than requesting music I'll supply it myself. You've got enough work on your plate reading through all of that and making a follow-up post.