They are purple flapjack octopus-like enemies that are encased in a ball of water, they have golden mustaches and turn dark-grey when they're on land without their water balls. When moving in this state, they leave a short wet trail that soaks the ground, causing it to have an uneven appearance.
They are normally found floating on the surface of the water in their water balls, occasionally making large vertical leaps. However, when Mario approaches, they shoot a powerful stream of water from their undersides.
If Mario captures one, he can use it to fly. The result is similar to F.L.U.D.D.'s Hover Nozzle for a limited time before needing to be refilled by touching water. He is also capable of spinning while shooting to the side to spray all around him, and the water can clean away lava as though it were goop, like the Squirt Nozzle.
Only a single Gushen appears in Mollusque-Lanceur's rematch and will give Mario unlimited water supply due to the constant raining.