Spheres Hub
Spheres tl;dr: Remnants of the CHAOS era when their boosts were more relevant, most spheres act as a very minor improvement to a character which makes your character feel more special for you to use. You get a sphere when you realize and max limit break + level an EX weapon to max (it becomes purple).
Spheres are just to make your favorites look better, though in certain cases, as noted below, can expand role coverage
All characters want ATK or BRV DMG up, both are very effective, other stats are not relevant
ATK vs enemies with high DEF
BRV DMG vs enemies with high BRV DMG Reductions
Note on ATK vs Physical/Magic/Melee/Ranged ATK vs BRV DMG:Â
Raw ATK boosts effect battery and HP Poison DMG while other listed stats will not.
Gladio/Snow/Basch if character can Lock
Gabranth/Celes if character cannot
Galuf if unit can evade often
Paladin Cecil for Encouragement armor
Ceodore, Braska or Minwu for Some extra healing
Iris for a party ATK boost
Maria/Llyud on healers/HP regen units
Alphinaud for units who buff often
Nabaat/Garnet on attackers who can be healed
Party ATK & mBRV +5%
(The strongest generic spheres)ATK spheres for all attackers
Seymour is best always
Auron for melee attacking debuffers
Irvine for ranged attacking debuffers
Kefka for magic attacking debuffers
Paine if character can hit weakness
Quistis for other supports