Here is the full list of all 40 METALLIC CHILD achievements.
Rescue 20 survivors.
Defeat the Metallic Child, Fira.
Experience a defeat in battle.
Visit the various facilities of Life Stream.
Defeat all Metallic Childs.
Defeat the Metallic Child, Graver.
Defeat the Metallic Child, Shutty.
Defeat the Metallic Child, Faceless.
Defeat the Metallic Child, Controd.
Defeat the Metallic Child, Spyden.
Defeat the Metallic Child, Flyer.
Defeat the Metallic Child, Lighton.
Defeat the Metallic Child, Icela.
Defeat the Metallic Child, Gigantic.
Defeat the Metallic Child, Magna.
Install 150 Mini-cores.
Install 200 bugged and viral Cores.
Install 150 Super-cores.
Clear all Virtual Missions.
Clear Terminal Creed.
Defeat 3000 enemies.
Deal 600 damage or more to an enemy in a single hit.
Accomplish 30 combos.
Accomplish = double kills.
Accomplish 100 triple kills.
Accomplish 30 fantastic kills.
Perform 200 Chain-skill attacks.
Go on camera 20 times, for Miamo's live stream.
Open Daviny's box 20 times.
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 an S for battle 100 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.