As you move around, the other character in the level will copy your animation pose even though that character has no logic or State Machine driving the different poses. While this example copies the player, it is possible to set up a non-playable character (NPC) with AI and a State Machine driving animations, then have another NPC that has no logic copy the pose through the Copy Pose From Mesh node to mimic the same behavior and logic.
When using the Copy Pose From Mesh node, in the Details panel, you can enable Use Attached Parent which will look for an attached parent and use it as the source if the Source Mesh Component is not valid.
Also, you can Copy Curves in addition to Bone Transforms, which will copy the curves that exist in the current Skeleton. If the curve list has changed, it will require the animation system to be reinitialized.