Upchuck (voiced by Dave Wittenberg) is a Gourmand (from the French word meaning glutton) from the planet Peptos XI (Peptos being the Greek word for 'cooked' or 'digested'). Upchuck first appears in the episode "The Visitor", when an alien named Xylene enters a code into the Omnitrix, activating the form. He's latest appearance was in the Season 2 finale of Ben 10: Alien Force.
Upchuck has four strong, adhesive tongues that can stretch to great lengths, allowing Upchuck to latch onto large objects and reel them in with relative ease. Upchuck's mouth and stomach can also stretch, allowing him to swallow and digest objects fairly larger than itself.
As a Gourmand, Upchuck possesses several acid-filled stomachs that dissolve almost all forms of matter, except ironically, ordinary human food. The items ingested are converted into explosive balls of liquids that can be expelled at will with great accuracy. Upchuck also seems to be able to take a surprising amount of punishment for a creature of its size, able to take the brunt force of a moving car impact as well as surviving after being thrown through a wall.
In the final episode Upchuck was able to grab the sub-energy from the Forever King and swing him around. The Sub-Energy gave Upchuck super speed for that while.
Upchuck is small with a green stomach, black suit, a green head and small green fingers but in the Ben 10 Alien Force episode "War of the Worlds (Part 1)" it showed an Upchuck with yellow skin, a brown and black spotted suit and the Omnitrix symbol was on his yellow stomach.
Upchuck is unable to swallow ordinary human food. In the episode 'Ben 4 Good Buddy', he remarks that he wasn't able to digest it. He is able to self destruct, probably after a continued amount of bad digestion. Upchuck also has a limit to how many big objects it can swallow.
Upchuck comes from the planet Peptos XI.A once great planet that used to be filled with exotic wildlife. Peptos XI was the center of trade in the universe but after a while the food supply ran low so to adapt to the harsh conditions on their planet the gourmands learned to survive on what they could. After a few years they evolved harder than diamond teeth, four long adhesive tongues and four stretchy stomachs filled with super corrosive acid that can be fired at will with great accuracy.Gourmands are literary eating machines they only eat inorganic food such as a car because of that their only weakness is they cannot eat human food such as pizza because they cannot digest it.