Here is the full list of all 52 Mega Man X Legacy Collection X achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Listen to 10 tracks for long enough with the Music Player, and then listen to the secret track.
Complete all X Challenge stages.
Watch Morph Moth's metamorphosis in Mega Man X2 without interfering.
Use Silk Shot to grab an item in Mega Man X2.
Use Nova Strike to score the final hit against a boss in Mega Man X4.
Use a Ride Armor to score the final hit against Magma Dragoon in Mega Man X4.
Check your own ranking in X Challenge.
Complete an X Challenge stage equipped with only the X-Buster.
Complete Zero's story in Mega Man X4.
Obtain the EX Item, and have max. lives, energy, weapon energy, and full Sub Tanks in Mega Man X4.
Use all of Zero's special saber techniques in a single playthrough of Mega Man X4.
Complete Mega Man X1, X2, X3, and X4.
Complete Mega Man X4 (cannot be earned in Rookie Hunter mode).
Complete X's story in Mega Man X4.
Obtain all four armor parts in Mega Man X4.
Fire fully-charged shots using all of X's weapons in a single playthrough of Mega Man X4.
Obtain the Hyper Chip in Mega Man X3.
Complete Mega Man X3 (cannot be earned in Rookie Hunter mode).
Obtain all four Ride Armor chips in Mega Man X3.
Obtain all four armor parts in Mega Man X3.
Reach Byte without a Ride Armor and win without the aid of special weapons in Mega Man X3.
Reach Vile MK-2 without a Ride Armor and win without the aid of special weapons in Mega Man X3.
Destroy Vile MK-2's Ride Armor (DRA-00) in Mega Man X3.
Reach Bit without a Ride Armor and win without the aid of special weapons in Mega Man X3.
Use Giga Crush to score the final hit against any of the eight Maverick bosses in Mega Man X2.
Complete Magna Centipede's stage without being spotted by a single searchlight in Mega Man X2.
View 20 images across all four titles, then change the wallpaper to the secret image.
Blast through the mystery of the staff credits and return to the future.
Complete the opening stage of any game in both the English and Japanese versions.
Receive Zero's arm part in Mega Man X.
Complete Mega Man X (cannot be earned in Rookie Hunter mode).
Use the Spiral Crush Buster to defeat a boss in Mega Man X.
Complete Mega Man X2 (cannot be earned in Rookie Hunter mode).
Cut Wire Sponge in half in Mega Man X2.
Obtain all four armor upgrades in Mega Man X2.
Complete the opening stage of Mega Man X2 with a full energy gauge.
Obtain all four armor upgrades in Mega Man X.
Obtain all Heart Tanks and max out X's energy gauge in Mega Man X.
Cut off Flame Mammoth's trunk in Mega Man X.
Destroy an enemy Ride Armor in Mega Man X.19
Knock off Armored Armadillo's armor in Mega Man X.
Defeat any of the eight Maverick bosses in Mega Man X.