Firstly, A pole shift is not what some believe it to be. People think a pole shift means that the Earth will flip upside down and completely rearrange the geography of the planet, THIS IS FALSE! A pole shift is a very natural occurence that has happened in the past and will happen again. When the poles shift it is simply the MAGNETIC poles that shift not the Earth itself. And it takes thousands even tens of thousands of years to complete a pole shift. The shift is proceeded by obvious signs, such as migratory birds becoming disoriented and unable to find their way south/north. While a pole shift is undoubtedly in the Earth's future, we see no signs of it's impending occurrence. The pole shift will not occur in 2012. You would be more likely to sprout wings and fly to Mars lol.

Secondly, Planet X IS NOT BELIEVED TO EXIST, hence the name Planet X. It is a theoretical body of space debris that astronomers use to calculate the possible response efforts mankind could attempt to thwart a collision with Earth. And it is also used as an example of how its possible for a large asteroid to pose a danger to Earth suddenly and with almost no warning.