Does my pet need to be trained to be a Service Animal?
Not necessarily, but the pet must be able to maintain a level of behavior conducive to being around other people. If your dog barks, growls, or otherwise acts out of control, places of business are within their right to exclude you from their premises. In that case, they should give you the option of continuing to enjoy their goods and services without the animal present.
Having a good foundation of basic obedience will only ensure that these situations not happen.