I'd say Buranchi loses both rounds with moderate effort on the 4 Beast's part. A major problem is stamina. In between his blinding speed he needs to charge back up, giving ample opportunity for the 4 beast to attack him in either scenario. The eternal lighting is a problem, but I'm not sure it could off the 4 Beast full form, and it could only affect 1 body in it's separate form. So yes, I'd say the 4 beast in both scenarios.