Yuck (Yin Yang Yo!)

Yuck is an Evil Level 5 Woo Foo Warrior who originally was an entity formed from Yin's obsession with control and Yang's aggression. Yuck wants nothing more than to become the most powerful Woo Foo Knight ever. And to do that, he needs to eliminate Yin & Yang plus Master Yo. In the episode "Upstanding Yuck", he became good, but Yin and Yang didn't believe him. In the end, Yuck turned evil again after Yin and Yang attacked him many times. Despite being half female, Yuck is often considered a "he" and lacks eyelashes, much like Yin and Yang's combined Aura. It was listed that Yuck is a bedwetter.

Abilities
Yuck, being a creation of Yin & Yang, has all their abilities, plus his own "Foonado" called a "Yuckicane". He has also been shown to use Energy Rays, Levitation, Foo Field, Fists of Fire, Foo-portate, Foo Orbs, Paws of Power, Bamboo Weaponry, Aura Swap, and Foo-Plicate (with the Foo-Plication Charm). He also seems to be able to possess people, as seen in the episode "Camp Magic Pants". He can also change into his muscular form at will. He also has superspeed and super strength and super jumping and he is super smart.

Relationships

 * Yang: Not much is shown about Yuck and Yang's relationship but it is known that Yang hates Yuck because he hurt Yin's feelings. It is shown in Imperfect Fooplicates that Yuck is also smarter then Yang, knowing math.
 * Yin: Many fans question Yin and Yuck's relationship and think that Yuck may have a crush on her; due to the events of "Falling Yin Love". But is most likley untrue as many times they fought as well.
 * Yo: Yuck hates Yo with all of his might because he refused to train him and Yuck even tried to kill him.

Last appearance
His last appearance was in the episode "personality problem", where it feeds on the aura of Yin and Yang to have more power, but in the end Yin and Yang manage to combine their auras to fight.

Yuck has no choice but to escape them, but is finally defeated when the Yin and Yang, beat him by pulling up a mountain.

It is not known what happened to Yuck, because after this episode did not appear in the series, probably Yuck has been redeemed after receiving such a beating.