FFX-2: Excellent Negotiator Achievement in Final Fantasy X / X-2 HD Remaster
FFX-2: Excellent Negotiator10
Use Bribe 30 times
How to unlock FFX-2: Excellent Negotiator
Bribe is an ability granted by the Lady Luck dressphere. You will earn this by winning the Sphere Break tournament in Chapter 3. See "Sphere Breaker" for more info on this mini-game. If you fail to win the tournament, you can still obtain this sphere during Chapter 5, but the opponent is twice as hard. I would suggest reloading your save if you fail to win the tournament rather than trying later.
With the Lady Luck sphere equipped, use Bribe in battle 30 times. This command gives gil to the enemy to receive an item, and costs more depending on the enemy's maximum health (not current health). The bribe counts even if it fails, so simply use it 30 times offering zero gil to unlock the achievement. You could even do it all in one battle.