Is there a coach bus that takes you from Brooklyn to Six Flags Gr8 Adventure (1 Six Flags Blvd., Jackson, NJ 08527) or somewhere near the area? Or some other way to get their that doesn't involve a car or multiple train/bus transfers?
You can take a bus to lakewood and then take the nj transit. You have to check that they are doing routes that day to the park. Or you can uber from lakewood. Its about half hour, depending which part of lakewood.