There is only one way that Batman could beat Sinister. He would have to fight him twice. In the first fight, Bats would quickly realize that Sinister is almost indestructible. His only chance damage and daze Sinister long enough to get a cell sample and escape to the Bat Cave to analyze it. After days of work, he makes a weapon that will negate Sinister's molecular powers. Even with this scenario, I would only give Bats 2.5/10. Otherwise, the best Batman can accomplish is a strategic retreat.