Here is the full list of all 47 ECHO achievements.
Finish the game on Ultra Hard
Look at yourself in the mirror excessively
Pick up every orb in every caste level
Collect all Voices
Complete the fourth Verse
Kill 3 Echoes by shooting a Sun
Complete the second Verse
Collect 100 Voices
Throw 20 Crystal Balls
Shoot 200 Echoes
Have Echoes know how to sprint, vault, use doors and walk in water at the same time
Traverse infinity for a while
Complete the first Verse
Finish the game on any difficulty
Take out a Hyper Echo
Complete the fifth Verse
Tag 100 Echoes
Collect a Voice by having an Echo strike it
Collect 50 Voices
Reach Chapter VI
Distract 5 Echoes at once with one Crystal Ball
Get Foster back
Line up and shoot 6 Echoes with a single shot
Get 4 additional Cell capacity slots
Push 5 Echoes at once with the Riot Gun
Reach Chapter V
Complete the third Verse
Make a 2 cell energy drop during a blackout
Collect 25 Voices
Play the whole piano piece during a blackout
Kill 10 Echoes with Crystal Balls
Get 2 additional Cell capacity slot
Have Echoes play the harp and piano at the same time.
Eat 5 pieces of fruit during a single blackout
Take out 47 Echoes with the stealth takedown
Collect 10 Voices
Reach Chapter IV
Push 50 Echoes
Get an additional Cell capacity slot
Use Area Scan 20 times
Eat 20 pieces of fruit
Pick up 50 Suns
Shout and get the attention of 8 Echoes at once
Reach Chapter III
Push an Echo over a railing
Line up and shoot 3 Echoes with a single shot
Activate the palace