As the in-game description says: creatures of the swamps of Nullwhere, Marshlings are strong dancers if you know how and when to use their power. They require 3 Gloom Buns to dance battle. Marshling is an ooblet that looks like a shadow wearing a mask. Its head looks like the top of a fruit. You can obtain Marshling through Friendship gifts or as a prize at the Dance Barn tournament. The common one has a purple tint, while uncommon Marshling features a light red color.