Here is the full list of all 40 METALLIC CHILD achievements.
Defeat the Metallic Child, Flyer.
Rescue 20 survivors.
Deal 600 damage or more to an enemy in a single hit.
Defeat the Metallic Child, Shutty.
Open Daviny's box 20 times.
Accomplish = double kills.
Defeat the Metallic Child, Icela.
Defeat the Metallic Child, Faceless.
Defeat the Metallic Child, Controd.
Experience a defeat in battle.
Be graded an S for battle 100 times.
Install 150 Mini-cores.
Defeat the Metallic Child, Gigantic.
Visit the various facilities of Life Stream.
Defeat the Metallic Child, Graver.
Defeat the Metallic Child, Fira.
Defeat all Metallic Childs.
Defeat the Metallic Child, Spyden.
Defeat the Metallic Child, Lighton.
Defeat the Metallic Child, Magna.
Install 200 bugged and viral Cores.
Install 150 Super-cores.
Clear all Virtual Missions.
Clear Terminal Creed.
Defeat 3000 enemies.
Accomplish 30 combos.
Accomplish 100 triple kills.
Accomplish 30 fantastic kills.
Perform 200 Chain-skill attacks.
Go on camera 20 times, for Miamo's live stream.
Help retrieve Sly's weapons 20 times.
Help deliver Trevon's virus case 20 times.
Defeat 20 of Catherine's modified robots.
Repair Schrodinger 20 times.
Be graded a D for battle 100 times.
Collect all Recor-Ds.
Collect all Fan-art.
Change weapons 100 times during battle.
Equip a drone 100 times during battle.
Perform 200 Take-downs.