The following persons may appear in a representative capacity at hearings or other legal proceedings:

(1) Individuals representing themselves or their business (pro se); and

(2) Attorneys at law duly qualified and entitled to practice before the supreme court of the state of Washington; and

(3) Attorneys entitled to practice before the highest court of record of any other state, if Washington attorneys are permitted to appear before administrative agencies of the other state, and if not otherwise prohibited by our state law; and

(4) Interpreters for persons with a limited understanding of the English language or hearing impaired persons; and

(5) Other persons the commissioners may allow, if a party shows a necessity or a hardship that would make it unduly burdensome to have one of the representatives set out above.