Since they can travel across the room very quickly, it’s usually best to shoot Desgeegaas (especially the large variety) from a distance. Small Desgeegas can be killed relatively quickly with Spazer beam weaponry or higher, but a Charge Spin Attack with any beam will kill them in one hit. For the large Desgeegas, it’s best to maintain some distance unless the Screw Attack is available. If it isn’t available, powerful beam weaponry can work well too, such as a fully-charged Ice-Wave-Plasma combo which will kill them with one hit.