Can someone give me advice on beating braskas final aeon?

Jecht is extremely powerful. I used stamina tablets on yuna and auron making them have 9500ish HP each, and his sword deals around 2000-3000 damage, and i keep bahamut on his overdrive and he has 7500ish HP max and i grand summon him on round 2 of jecht use his over drive which gets 40-50000 to him, and then sometimes i get to use a second overdrive and sometimes i dont because he kills me. and holy from yuna gets 9999 on him, which im not rly sure how to get more than that. Plz HALP