with this there should be no need for elixers or cheats.

well what i did is i went into battle with 2 characters dead which makes him stab his claws into the ground. now i used cloud,cid and redxiii. any characters on high enough leveles and correct materias can win though.

my set up.
cid (Limit up + hyper)
final attack(mastered)-phoenix(Masterd)
sneak attack-any summon(non fire elemnt)
master magic
Hp<->Mp
counter(if you have 3)-any summon(non fire elemnt)

cloud (dead)
master summon
enemy skill (white wind and great guard or big gurad whatever?)
counter(if you have 2)-any summon(non fire elemnt)

red xii (dead)
master magic
counter-bahamut zero(mastered)
bahamut zero(3 stars)- quadra magic (mastered maybe i forget?)
that combination will allow you to counter his hits with 4 bahamut zeros.

ok so start the battles if sneak attack works nice if not dont sweat it. hit him with Limit. if rubys next attack doesnt kill you hit him with knights of the round. and do so until cid dies. when cid dies everyone will be brought back to life by phoneix.

next have cloud whitewind eveyrone (know where spells, summons, and enemy skills are so you dont waste time looking for them). Have redxiii hit him with kotr. if someone dies from the attack dont worry about it cause when cid dies(assumeing he didnt die) he will bring everyone back to life. but i suggest on clouds next turn to cast great guard or big guard? cloud, redxiii and maybe even cid will survive his attacks more often. and everytime they get hit they counter with a summon. and red xiii hits him with 4 bahamut zeros. still hit him with kotr as much as possible.

whenever you see limits come up i suggest useing them its a nice way to get in a couple 1000 damage without being countered with ultima. if your useimg mime materias you can mime kotr instead of always trying to cast it. make sure your MP is up on everyone. keep ethers at the top of your item list to be safe. you might start to notice his ultima missing your characters more and more often. never cast phoenix manually let the materias themselves do it. only use life spells or phoenix downs after phoenix has run out of times it can use itself. but if this stratagy was done correctly you should beat him by your last time you were able to use phoenix oh and if luck is on your side

a good basis of this stratagy is hopeing ultima misses and that he doesnt target cid with all his attacks all the time. but ive used this stratagy and beta him many many times.

good luck