Heat up your grill over its medium setting or prepare charcoals for grilling.
Wash the blueberries and transfer to a large mixing bowl. Add the sugar and flour and stir well to combine. Transfer the mixture to an 8"-square disposable baking pan.
Place the pan onto the grill on direct heat and close the lid of the grill. Cook for 10 minutes, then stir briefly. Cook for an additional 5-10 minutes, until the blueberries have largely released their juices and the mixture has swelled up.
Top the blueberry mixture with the biscuits in one layer. Close the lid of the grill and cook for 5-10 minutes, until golden brown.
Remove the pan from the grill (carefully! it will be extremely hot). Let cool slightly before serving.