Assume that X is the importer and Y is the buyer.
X can register the vehicle under Ys name or Y can get all documents from X and get it registered under Y's name. IN both these cases, Y will be the first owner.
You need the following documents (excerpt from motortraffic.gov.lk). You probably won't need the documents which I have striked out.
MTA – 2 Application Form
Two 2.0 x 2.5 inch photographs of the owner of the vehicle (The Grama Niladhari of the relevant area or the vehicle importer should certify on the reverse of the photograph) A photocopy of the national identity card, driving license or the valid passport of the owner of the vehicle. Custom entry (custom 53) Originals of receipts for customs duty payments (Assessment notice) In case of a brand new vehicle, the relevant invoice. In case of a reconditioned vehicle, foreign registration certificate (with the English translation) If the vehicle has been imported with an import permit, the relevant permit. For registration of absolute ownership, the relevant MTA-3. In case of registration with a mortgage, a copy of the mortgage deed. In case of a vehicle obtained at auction held by the customs, three armed forces or courts, the letter obtained from the relevant authorities and the receipt.. For vehicles that were shipped subsequent to 01.03.2007 and coming under H.S. codes 8702, 8703, 8704 and 8705, pre-export examination certificate. For brand new vehicles, prototype of the relevant vehicle model or the relevant weight measuring certificate. In case of registration under the name of a business, a photocopy of the registration certificate of that business. Motor vehicle examiner’s report for motor vehicles. 02 postcard size colour photographs depicting the front and the body of the relevant vehicle. (Chassis Number should be mentioned and the applicant should sign them.) In case of a motor bicycle, the packing list certified by a motor vehicle examiner. In case of an imported reconditioned motor cycle, in addition to the customs document, the engine and chassis numbers should be certified by a motor vehicle examiner. For a motor vehicle produced or assembled in this country, the letter by the Assistant Commissioner approving the chassis and engine number should be submitted. When imported on duty free concession, duty free permits.