The whole pumpkin occupies a large space in the freezer and moreover storing it in an airtight container is essential. So it's not practically possible to store the whole pumpkin in a container. The best option is to cut the cooked whole pumpkin into chunks, store them in a freezer-friendly container or in a ziplock bag and pop them in the freezer.  I would suggest storing diced pumpkin as the whole pumpkin occupies a large space.  Since the whole pumpkin is kept open in the freezer as it's practically impossible to store it in a container, the chances of catching odour from other foods are higher.