If you are buying a Pembroke from a good breeder, the odds are they will be either natural bob-tailed or docked, since that is what the AKC standard calls for. Someone who breeds strictly for performance, and not the show ring might leave the tail, but I wouldn't count on it. Especially since they are done at only a few days old, and there is no way of knowing which puppy will be going to what home at that age.
If you are getting a Cardigan, then it will have the tail left, since that is the standard, and the only reason a Cardi would be docked is an injury or something.
If you are getting a Cardigan, then it will have the tail left, since that is the standard, and the only reason a Cardi would be docked is an injury or something.