Here is the full list of all 69 Final Fantasy X/X-2 HD Remaster achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Obtain all available FINAL FANTASY X-2 achievements
Complete 100% of the main story
Defeat Vegnagun
Obtain all dresspheres
Defeat Trema
Listen to all of Maechen's stories
Obtain treasure in the Tonberry area
Roll the same number on all the Gambler's Dice
Catch the Amazing Chocobo
Obtain Magical Dances, Vol. II
Complete Shinra's Bestiary
Reach the 10th floor of Iutycyr Tower
Reach the 20th floor of Iutycyr Tower and defeat the boss
Reach the 40th floor of Iutycyr Tower and defeat the boss
Reach the 60th floor of Iutycyr Tower and defeat the boss
Reach the 80th floor of Iutycyr Tower and defeat the boss
Complete an episode in Chapter 5
Win a blitzball match in FINAL FANTASY X-2
Defeat Zalamander
Pay off O'aka's debt
Win 10 times at Sphere Break
Learn 5 Blue Bullet skills
Achieve a 99 chain attack
Complete the ability set for one dress
Change dresspheres on Yuna, Rikku, and Paine in one battle
Defeat Bahamut
Open the chest that includes the Ribbon in the Bevelle Underground
Help Clasko catch a chocobo by the end of Chapter 3
Reach the highest level (LVMAX) in Gunner's Gauntlet
Defeat YSLS-Zero
Obtain one special dress
Obtain all available FINAL FANTASY X achievements
Buy every sphere at the Luca Theater
Deal 99999 damage with one attack
Defeat Nemesis
Defeat Penance
View "Eternal Calm"
Complete a Sphere Grid for one character
Complete the Sphere Grids for all main characters
Learn to use all enemy abilities
Find all 26 Al Bhed Primers
View one complete fiend tale
Defeat Yu Yevon
Defeat Seymour Omnis
Spend 100,000 gil or more in bribes
Obtain all Jecht Spheres
Use Bribe 30 times
Unlock all slot reels
Steal successfully with Rikku 200 times
Use Mix 30 times
Obtain all Celestial Weapons
Obtain Magus Sisters
Obtain all Aeons
Obtain Anima
Win a blitzball tournament
Pass all chocobo training
Win a race with a catcher chocobo with a total time of 0:0:0
Defeat Yunalesca
Obtain Yojimbo
Get 5 treasure chests during the Chocobo Race at Remiem Temple and win the race
View the "Underwater Date" scene
Do 9999 damage or more in a single attack
Dodge 200 lightning strikes and obtain the reward
All party members come together
Win a blitzball match in FINAL FANTASY X
Learn the Jecht shot
Clear the Besaid Cloister of Trials
Find 1 Al Bhed Primer