The Pocket Medic differs in appearance based on the class equipping it. If it is equipped by the Soldier, both the doll and the pocket are bright and team-colored, whereas for the Heavy, the doll is team-colored but has a darker tone to it. The pocket is not team-colored and has a dark color by default.
When players equipped with this item kill an enemy unassisted by another player, the killfeed shows everyone in Pyroland that it gets the assist, with its custom name if it has one.
[Undocumented] Pocket Medic is now credited with assists on unassisted kills.
"Pocket Medic" is a term coined by the community to refer to a Medic who exclusively heals one patient, never taking his heal beam off him. A Medic may tend to stick to a Heavy or Soldier due to their high health and damage output.