To form a company, two basic founding documents are necessary:

Memorandum of association
It contains the fundamental conditions upon which the company is allowed to operate. The document consists of information like firm of the company, data on the founders, information about the equity capital of the company, admissible amount of the foundation expenses and their payment order, etc.;
Articles of association
It generally defines the responsibilities of the board, the type of business to be executed, and means by which the owners exert control over the board of directors. Upon consent of the founders the Articles of association may include specific provisions regarding decision making, restrictions of the board, competence of the council, other specific conditions regarding the process of shares transfer.
Other secondary documents may be demanded. These are as follows:

An application of the local commercial registry – every state has its own form that must be submitted for any changes to take place;
Declaration of each board member / Consent of board member; List of shareholders / A division of the register of shareholders (for limited liability company);
Declaration of company address / Announcement of an office address;
Bank notice on the payment of the equity capital;
Receipt for payment of the state fee;