Nibiru is a hoax. There is no such planet. The are a lot of hoaxes on the Internet, but this one is especially strange, because there is no evidence whatever for its existence, and past predictions about it hitting the Earth several years ago were obviously wrong.
Pluto is being pulled gravitationally by everything in the universe, with the Sun, Jupiter, Saturn, Uranus, and Neptune dominating. There is nothing strange about its orbit, and no evidence of any massive objects orbiting the Sun beyond Pluto: no undiscovered planets, nearby stars, or brown dwarfs. I donít know where you have heard such rumors, but probably not from any reputable science source.