When you say shifter I am thinking you mean Were. We have werewolves that are people who can change into wolves. Then we have the sub species of weres: Wereleopards, Wererams, etc. These people are just like werewolves but they change into a certain animal. There isn't a species of were that can change into more then one animal.
Silver doesn't hurt weres. Mountain ash, mistletoe would. Have your friend look over the werewolf information.