A petitioner for a Treaty Trader (E-1) or Treaty Investor (E-2) visa must first satisfy that the business or enterprise is set to meet the wants of the law, and adheres to the numerous requirements for the E2 visa classification. It is up to the consular officer to provide the applicant with forms for this end.
The petitioner can anticipate for the consular officer to require more documentation, to form an assessment about eligibility for a treaty trader or treaty investor visa under the law. It is quite impossible to know the precise documentation needed since circumstances change greatly from one applicant to the other end.