So I'm about to start running an "evil" Pathfinder Campaign in a homebrewed setting in which the PC's are going to start in prison. All of them have been sentenced to death and are essentially on death row in an Alcatraz styled prison. After a short introduction and maybe some roleplay the PC's are going to be brought before some high ranking official in the government of the country they were imprisoned by. Now, not to give too much away (in case one of my PC's stumble across this randomly), but the "government official" is going to be a Phistophilus (aka Contract Devil) however, I'm making a few minor changes for aesthetic purposes and "flavor." The first is that the devil's infernal contract ability will be made with a handshake that will leave a mark similar to greater brand rather than a written contract, other than that, the ability is essentially unchanged.
The change I wanted some assistance on though is that I want the devil to be able to use alter self (without modifying it's ability scores) to take the form of a humanoid at will. It would be similar to what the Kitsune have only it wouldn't have to be the same form each time. What I'm wondering is, should I get rid of one or more of it's other spell like abilities to compensate? If so, which one(s)? If not, should I raise the devil's CR?
EDIT: I should probably also mentioln that this devil won't be used as an encounter in the first session but will likely be in an encounter at some point.