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