I couldn't miss the chance to practice my drawing!
Auron is an optional boss in Final Fantasy X-2: International + Last Mission and the Final Fantasy X-2 HD Remaster. He is fought in the Fiend Arena in the final tournament, the Farplane Cup. Auron will join the party after being defeated.
Once Auron has been defeated in the Fiend Arena and the player reaches the end of the Farplane Cup, they will be given the option to recruit him. He can learn his Overdrives from Final Fantasy X, Shooting Star and Dragon Fang, by being hit by strong attacks or by being ejected from battle while fighting himself in the Battle Simulator/Farplane Cup. If he is released from the Gullwings, he can be recruited again the same way he was first recruited.
Auron can eject all party members out of the fight.
One should equip the Mascot dressphere and be at a decent level (at least 60). Yuna's Moogle Beam and Paine's Cactling Gun combined with a physical attack from Rikku deal around 50,000 damage each time.