Here is the full list of all 24 Mega Man Legacy Collection achievements.
Take out the Alien and complete Mega Man 2.
Stop Dr. Wily's plans and complete the original Mega Man.
Turn Gamma to scrap metal and complete Mega Man 3.
Escape the Skull Castle and complete Mega Man 4.
Discover the truth about Proto Man and complete Mega Man 5.
Unmask Mr. X and complete Mega Man 6.
Complete all six Mega Man games.
Earn 1 bronze medal by completing a Challenge.
Earn 10 bronze medals by completing Challenges.
Earn 25 bronze medals by completing Challenges.
Earn 50 bronze medals by completing Challenges.
Earn 1 silver medal by completing a Challenge.
Earn 10 silver medals by completing Challenges.
Earn 25 silver medals by completing Challenges.
Earn 50 silver medals by completing Challenges.
Earn 1 gold medal by completing a Challenge.
Earn 10 gold medals by completing Challenges.
Earn 25 gold medals by completing Challenges.
Earn 50 gold medals by completing Challenges.
Complete the Dr. Wily Forever Challenge.
Complete any Challenge marked with "NO ITEMS."
Complete the "ALL APPEARING BLOCKS" Challenge.
Complete the "ALL ROBOT RUSH" Challenge.
Complete the "ALL ROBOT RUSH (NO ITEMS)" Challenge.