Page ten of the application form itself lists a number of documents that you must submit. There is no exhaustive list that you should submit, since each case is different and your particular details may mean that you need to submit documentary evidence to prove a particular part of the form.
She will though have to submit:-
1. Her passport.
2. Evidence of her leave to remain in the country from which the application is made (eg. Norway if it is to be Norway)
3. Documentary evidence of how you are to pay for the trip, so bank statements from the previous year for you both showing the funds available to you both during your stay evidencing the fact that you will not require access to public funds during your stay.
4. Criminal records if she has committed a crime
5. Evidence of her continuing obligations where she is living (or to live following marriage). For example, evidence of continuing employment (eg. contract of employment, letter from her employer), accommodation (tenancy agreement, land title deeds) and responsibilities
5. Divorced decree if she has been married before
6. Evidence that she intends to leave the UK after marriage, flight tickets or onward travel information
7. Statements from you both confirming your plans to marry, full details, and your plans following marriage (ie. that you are to become resident in some other country to settle
8. Evidence that you are in fact to get married (booking of a venue for marriage, correspondence between you, evidence of invitations to the wedding.
I trust this clarifies, if so please click accept.