Ghost pokemon have a long and rich history here at Lake Eeree, and everyone who has chosen to play a ghost has had a unique method of portraying it. However, we have had recent problems relating to abuse of ghost powers. Rules governing ghosts and illusion-type tricks have been outlined here:

Ghosts cannot breed. They are not born, but created when something dies. Ghost pokemon are spirits that linger on in the world unable to find rest or a sense of finality. Their mission in the living world is not yet complete. Ghosts cannot/do not eat plants, the flesh of other pokemon or anything else material. They survive and strengthen on the emotions or confusion shed/created by the living.

Light--daylight or otherwise--hurts ghost type pokemon. Their powers are lessened or broken in the presence of light. A ghost would feel most powerful in the dark and stick to the shadows. They can enter other characters' bodies and step into other characters' dreams, but only with player permission.

Illusions are only optical.... a ghost isn't able to be touched without someone knowing it isn't what it appears to be. No one could mistake a ghost in disguise for smelling like the thing it isn't; lack of smell would give it away.

Illusions fall under the rules of psychic powers. A character could actually refuse to see a ghosts's disguises because of the interaction rules. A ghost, or any character, can not have absolute power over other character's perceptions of reality.

Sending messages back and forth all over the land also applies to the psychic power rules, even between two characters owned by the same player.

A ghost isn't powerful enough to trick everybody; someone the ghost is not aware of should be able to see right through it. It has to be mentally imposed on another. Illusions would only appear to those who believe in them. Players always have the option to expose this kind of trickery, simply by not being influenced by it--just as an attack can be thwarted by players in battle.

A dark type pokemon wouldn't be affected by illusions.