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