Halloween Companions like Charlotte the Witch and Necrotic Cabby can only be exchanged with other Halloween Companions and it will not be possible to exchange them with other cats.
* All Halloween companions can be exchanged between them. For example, you can swap Floating Gospel with Looney the Bewitched . *
The Crows can simply be exchanged with other Crows , since the different kinds of birds are not of the same species.
For example, you will not be able to trade a Raven with a Falcon .
* Although the Raven is released during the Halloween update, it is not considered a Halloween Companion and therefore you will not be able to exchange it with the Halloween Companions. *