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