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