In Omniverse, 16-year-old Perk Upchuck does not wear clothes and his eyes are recolored green. He wore the original Omnitrix symbol on his left hand. In the Original Series, Perk Upchuck had white eyes and wore a black open-front suit with white over-sleeves and white bands around his legs and white padding under his three-toed feet. He has whisker like lines on his face, and a green tail.
Perk Upchuck is a vaguely humanoid amoeba-like creature with green skin, six sprout-like growths on the back of his head, a dark-green patch of skin on his head, light-green skin on his face and belly and a crooked teeth overbite.