Generally, Yin has a good sense of right and wrong, and usually does the right thing. It has been shown, mostly in the current season two, that she likes "bad boys", but she has said it was just a phase. She can also be vain and self-centered at times.
In the episode "Night Fall", upon discovering Coop was working for the Night Master, she gained an attraction to him. However, this attraction faded away upon knowing that Coop had his evil under control.
It was because of this personality trait that Yin temporarily became evil through Coop's influence, and went on a rampage across town with him, to prove that she was evil enough to be the Night Mistress (with him as the Night Master), something which Yang believed could trigger "The Dark Tomorrow".
With her brother, she can do combination attacks such as Fire-Nado, Yin-Cinerang, and Fists of Yin-Cineration. With Master Yo, she can do Yin Yang Yo-Yo. With the Woo Foo Battle Cruiser, she can do Transfoo-Shrinkmafy.
She also has the power to float and fly. She is skilled at using a bamboo staff in fights and, due to being a rabbit, has a super jumping ability. She also has superspeed and has great physical strength.
In the Season 1 finale, it has been shown that while Yin is mostly studying the mystic side of Woo Foo, she is as powerful in the martial arts side of Woo Foo as her brother. It was also during this episode that she helped to save the world from eternal darkness (the Night Master's goal so he could be unstoppable), along with Yang, Master Yo, and Coop.