Save Scum Method has now been patched (26/02/23). I'll leave the video below for anyone who might be curious what that was.I've just started a new game today to complete this achievement correctly in one sitting. There's a total of 35 different enemy types/variants in the game, however you only need to scan 22 to get the achievement to pop. I managed to get the achievement shortly after stepping off the train and scanning Hedgie within 4 hours. Here's a list of all mobs in the order of their appearance.
Mobs Listed By First AppearanceVOV-A6 Lab Tech (White Humanoid Unarmed)
VOV-A6 CH Lab Tech (Black Humanoid Unarmed)
Dandelion (Security Camera)
WSP-9 Pchela (Blue)
GMC-69/P Vatrushka (Rolling Turret - Red)
GMC-69/O Vatrushka (Rolling Turret - Yellow)
WSP-9 Laser Pchela (Yellow)
LUC-1 OWL (Unarmed)
GMC-69/L Vatrushka (Rolling Turret - White)
Mutant (Standard)
Mutant (Poison)
Mutant (Fire)
RAF-9 Engineer (Non-hostile Robot)
LUC-1 Laser OWL
Mother
Sprout
Sprout (Fire)
Large Mutant
WSP-9 Patrol Pchela (Red)
MFU-68 CP Duck
MFU-68 Labourer
VOV-A6 Lab Tech Series Shield (White Humanoid Batton)
Hedgie - Exhibition Boss Fight
ARU-31 Rotorobot - (Twin Bladed Robot)
Plyusch - VDNH Boss Fight, Pavlov & Testing Ground 9
MED-6 DOC (Two Legged Medical Robot)
LUC-1 Rocket OWL
Belyash - Theatre Boss Fight & Testing Ground 8
Sprout (Poison)
Natasha - Theatre Boss Fight & Testing Ground 12
Mutant (Nurse)
Large Mutant (Poison)
Large Mutant (Fire)
Dewdrop - Lighthouse Boss Fight
Twins Left & Right - The Twins Boss Fight