This is my technique on how I beat Neochu (Mission 55) in 2:52.
PARTY: Vanille (Leader)/Lightning/Snow
-Beaten Game (Therefore unlocked Stage 10) -Mission 55 unlocked -Party members must hae MAXED out primary roles -Each member should have over 18000 HP (Including Vanille) -5 TP - A bit of skill would help :P
Start off with deck 1. Toss a librascope REALLY fast (Try to get it in before you get knocked in the air.) Now let Snow take all the Damage, with lightning healing him at ALL times. With Vanille, simply spam death. EVERYONE knows that the hardest part of this battle is after killing Neochu, so just pray you kill him quick. If Snow has low HP, switch to deck 2 to heal him, then switch back. If Neochu casts Pollen or Screech, just retry the battle (Theres no use in wasting time healing after that.) Once he's dead, its time for something a bit unorthadox.
Switch to deck 3. Using Vanille, spam Firaga. Let snow take the damage, and switch to deck 2 if he needs healing. Now once the Picochu's have taken about 30000 damage, about 15 firaga's, summon Hecatoncheir. Now let him fight, while you spam firaga. Once youre about to die, go gestault. Now hold down the down button, and rapidly press A/X. This will raise the Picochu's stagger gauge really fast. Once you have 1 gauge left (It will stop automaticaly) use Gaein Salve Lv. 3 and it should stagger them all, and kill em all.