Yang's training with Ultimoose threatens his partnership with Yin; Yin and Yang's assignment to watch Yo's pet rock quickly gets complicated when the rock takes on a life of its own.

Carl tricks Yin and Yang into fighting each other after giving them a television with only one remote control; Kraggler, one of Yo's old rivals, turns everyone in town into elderly people when Yin and Yang criticize his age.

In an attempt to banish their negative traits, Yin and Yang accidentally create an evil version of themselves called Yuck; Yang goes after a large steel beetle to win over a girl.

Yin and Yang try to teach Yo that it's not good to boss kids around; Yin and Yang get into a fight while cleaning their room.

When Yin contracts Woo Foo Flu, Carl kidnaps her to take advantage of her illness' reality-warping symptoms; Yin and Yang spread lies in a bid to gain fame, but their fibs cause big problems.

Yang, eager to advance to the next level of his training, employs the Glasses of Unlimited Smartness; Yin loses control of her Woo Foo aura, which runs rampant across town.