Soul Manipulation is the ability to interact with one's soul or the souls of others. This ability ranges from being able to project the power of one's soul outward, grasping and ripping the souls of others out of their bodies, outright consuming souls to gain power, among other applications.
Generally speaking, we judge the potency of Soul Manipulation both by what it can do and by how many people its user can affect at once with it. This may range from only a few people at a time to entire planetary populations.
When judging the potency of Soul Manipulation, and the resistance against it, there is a variety of factors to be considered. Such as the mechanisms involved, how many people the Soul Manipulation can affect, whether it has demonstrated to break through resistances, how great the effects are, etc.
It should be noted that the ability to interact with souls and other non-corporeal entities directly as if they were physical objects is usually considered Non-Physical Interaction and does not grant the user the ability to manipulate souls in other contexts.
Under normal circumstances, most characters are assumed to have a soul by default unless the original medium specifies otherwise. Those who do not possess soul are usually considered to be immune to most applications of Soul Manipulation.