Poodles tend to be a little too energetic to make good guide dogs. They are smart, but more independent-minded generally, and easily distracted. A good guide dog needs to be happy spending hours at a time staying very still, and staying focused. While there are exceptions to every breed stereotype, they are just that - exceptions.

Different breeds have different strengths, and different uses as assistance dogs. I met a JRT who naturally alerted people to epileptic seizures, an ability discovered when his human worked as an overnight counselor in a home for children. Many kinds of dogs are good "pet therapy" dogs. Terriers are often trained to be picker-uppers for people in wheelchairs or with limited mobility. The list can go on and on.