There is no physical abuse. However, one of the main characters (a child) lives with her grandpa, who seems to be emotionally abusive. Or at least, as emotionally abusive as a character can be in a comic that is meant to be safe for children.
A character hits a pane of glass and gets a nosebleed. This only happens once and is one of, if not the only, instances of real blood being shown in the comic.
There is a character who frequently drinks sugary beverages in a bar-like setting. The setting of this particular scene and event appears to reference alcoholism, however no actual alcohol is used.
There is a character who is implied to have an addiction to sugary beverages. There are no actually dangerous substances used. However, it should be noted that this scene takes place in a bar-like setting (not a place that sells actual alcohol, but a place that resembles one).
Someone tries to beat up a dog. Another character defends and rescues it. Nothing graphic is shown, and the dog seems pretty apathetic about the whole thing.
Multiple characters are "mediums", partially possessed by the spirit whose powers they borrow. The protagonist is also possessed by an unknown spirit which only speaks in one scene. He seems unaware of this.