XCOM 2

Personal Combat Sims (or PCS) are neural enhancements that permanently increase a soldier's stats. There are three types (Basic, Advanced and Superior) and five stats that can be increased (Speed, Conditioning, Focus, Agility and Perception). Each soldier can equip one PCS, via the Loadout screen from the Barracks in the Avenger but you are free to overwrite that PCS if you find a better one. You cannot, however, reuse a PCS once it has been equipped to a soldier. Any soldier class can equip any PCS and you can't really go wrong with your choices but you should assign each PCS to a class that makes sense e.g. Mobility/Dodge to a Ranger or Aim to a Sharpshooter.

PCS can be found as random loot from slain enemies or purchased from the Black Market using Intel. You can also increase the benefits of PCS by purchasing the Integrated Warfare enhanced from the Guerrilla Tactics School. PCS tend to be relatively rare during playthroughs (I usually end up with 5-10) so save them for the soldiers you use the most. You only need to equip one PCS to a soldier for this trophy.

For more information about the PCS: LINK