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
Change dresspheres on Yuna, Rikku, and Paine in one battle
Listen to all of Maechen's stories
Complete an episode in Chapter 5
Win a blitzball match in FINAL FANTASY X-2
Defeat Zalamander
Defeat Bahamut
Help Clasko catch a chocobo by the end of Chapter 3
Complete the ability set for one dress
Pay off O'aka's debt
View one complete fiend tale
Defeat YSLS-Zero
Obtain one special dress
View "Eternal Calm"
Defeat Yu Yevon
Defeat Nemesis
Find all 26 Al Bhed Primers
Obtain all Jecht Spheres
Spend 100,000 gil or more in bribes
Deal 99999 damage with one attack
Defeat Seymour Omnis
Obtain all Celestial Weapons
Obtain all Aeons
Obtain Magus Sisters
Obtain Anima
Steal successfully with Rikku 200 times
Defeat Yunalesca
Win a race with a catcher chocobo with a total time of 0:0:0
Pass all chocobo training
Obtain Yojimbo
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
Learn the Jecht shot
Find 1 Al Bhed Primer
Clear the Besaid Cloister of Trials
Obtain all available FINAL FANTASY X achievements
Dodge 200 lightning strikes and obtain the reward
Buy every sphere at the Luca Theater
Get 5 treasure chests during the Chocobo Race at Remiem Temple and win the race
Complete a Sphere Grid for one character
Unlock all slot reels
Learn to use all enemy abilities
Complete the Sphere Grids for all main characters
Defeat Penance
Obtain all available FINAL FANTASY X-2 achievements
Win 10 times at Sphere Break
Use Mix 30 times
Learn 5 Blue Bullet skills
Use Bribe 30 times
Roll the same number on all the Gambler's Dice
Open the chest that includes the Ribbon in the Bevelle Underground
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