Late-90s book about teenagers who transform into supernatural creatures

I'm trying to find a book I read as a young boy mid 90's to very early 2000's, I believe. It featured a team of teen humans who had the ability to transform into various supernatural creatures.

I believe the setting was based in the United States or at least North America.

I remember vividly two characters:

1. 
   

   There was a lycanthrope , I remember a name... which is either Kodiak or Kody/Cody. I believe this character also had a love interest within the team.

   
   


2. 
   

   There was a character who was stereotype alien-like (thin with large head), but I believe was a ghoul or demon of some sorts that is noted to cause accidents in North America. I cannot quite remember if this was a creature in the fictional universe or one of the teens could transform into it. I believe it might be the Dover Demon.

   
   

I also remember that the cover, the first few or last pages or so had a list of the creatures and short profiles.