The following equipment combination is very effective. Note: Genji armor is obtained by getting the DMW completed 100%. The Brutal and Gold Hairpin can be found in the "Seeking Priceless Items" missions. Mog's Amulet can be bought, and Ribbon is obtained by completing the "Seeking Priceless Items" mission category.

Materia

Hell Firaga (Magic +75)
Libra (Attack +68)
Status Ward (HP +999%)
Mug (Vitality +100)
Wall (MP +400%)
Curaga (Spirit +84)

Accessories

Mog's Amulet (foes drop rare items only; all steals are rare, Luck +5) or Ribbon (immune to all status ailments but Death)
Genji Armor (Break HP limit; new limit 99,999, always endure and regen)
Gold Hairpin (Break MP limit; new limit 9,999)
Brutal (Break Damage limit; new limit 99,999)