As I recall Dust Man is only called Dust Man because of a Japanese usage of the English word "dust" to mean garbage. So it's really compacted trash he shoots. Granted, it's still unclear why Skull Man would be weak to trash.
Skull Man comes up to Dive Man and does his thing, which disgusts him, making him accidentally launch a bunch of missiles on Drill Man, who out of rage shoots a drill into Toad Man's eye, which sprays the Rain Flush all over Spark Man. Spark Man can't resist the Rain Flush and his bulb goes insanely bright, which dazes Pharaoh Man, who looses control of his powers. This then kills Ring Man through some curse, making him go all Hedgehog mode and loosing his rings, which then stuffs Dust Man's Vaccum.