Min pins can be quite high strung.

And both chihuahuas and min pins can shed quite a bit.

My first thought when I read the requirements was a toy poodle from a good breeder or a rescue that utilizes foster homes.
My reasoning for this is that toy poodles are one of the most popular puppymill bred dogs IMO. So if you want a stable temperment you will have to go through a good breeder who breeds mentally sound dogs, or through a foster home that evaluates the dog's temperment.

Like others have mentioned the only downfall to poodles is their grooming requirements, but if they are kept in a shorter more practical cut they wouldn't need to visit the groomer as often.

Here is a link to the AKC poodle standard

http://www.akc.org/breeds/recbreeds/poodle.cfm

And a link to the Poodle Club of America

http://www.poodleclubofamerica.org/

Good luck in your friend's search.

Oh and one side note.... although they would fit into a little carry bag, they do have legs and can walk.........