ok it may take time 2 prepare but its well worth it. (i,ve researched and i believe the US version is not different to the international. so it should still work in your version)

well firstly u will have to have captured enough Monsters to have unlocked the Area Conquest super boss Don Tonberry. he is critical...

your overdrive mode should be set to stoic. you will need a weapon with the move's-*Overdrive to ap*,*Triple overdrive* and *triple AP*.

Over drive to ap- u can create with 10X door to tomorrows. if u capture every monster for SIX areas, u will get 99 of these!

Triple Overdrive- u can create with 30X winning formula. capture ONE of EVERY monster in Spira, and u will receive 99 of these.

Triple AP- u can create with 30X wings of discovery. to get them u can bribe a Marlboro and receive approx Wings to Discovery x4 for 540,000 gil. at (Calm Lands or Cavern
of the Stolen Fayth).

Or Great Marlboro and receive approx Wings to Discovery x8 for 1,280,000 gil. at (Sin or Omega
Ruins).
You can also Open 3 treasure chests in the Remiem Temple chocobo race without touching any poles, and you'll recieve 30 (ONE TIME ONLY!).


If u need money for bribing, then equip the move Gillionaire and fight mimics in Omega ruins. to get gillionaire Capture at least 1 of each monster from the Omega Ruins for the Monster Arena, and the trainer will give you 60 designer wallets. 30 is enough for gillionaire.

ok, customise abilities to your character weapon. and then let those with them fight Don Tonberry. everytime u hit him, he will counter with Karma, which will do LOTS of damage (the more enemies u have killed, the more it will do). However, because of your abilities, the hp damage that is converted to overdrive increase, will increase the number of ap u receive after battle. revive the character who died(he will) and repeat this. when the Don Tonberry STOPS countering, run away! otherwise he will destroy u. and then look at the HUGE ap u hsve just received . now heal, save and repeat, and your have completed the sphere grid in no time. (now MASTERING the sphere grid is another matter, but just concentrate on this 4 now).

if u have ANY problems with this, post it here and i will do my best to help...hope i,ve been useful.

EDIT-hey, curse u Jolts
.