How pluto consider as planet?

What are the additional two planet that was discovered?

Pluto has recently been reclassified as a Dwarf Planet/Plutoid.
What 2 "planets" are you referring to?

There are only 8 discovered planets orbiting around the Sun.

As of the time of writing, we have discovered 296 planets orbiting other stars.

You might be referring to the objects found in the Kuiper Belt that rival and maybe surpass Pluto in size. I don't think they have been given official names yet (one discoverer wanted to call one of them Xena).

Pluto has been re-classified as a dwarf planet.
Than there is what is called planetX, another dwarf planet far outside the orbit of Pluto.
Also there is another dwarf planet called Xena, even further out.
A dwarf planet is more an asteroid that was big enough to become a sphere.

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The International Astronomical Union has recently settled on the name "plutoid" to describe dwarf planets like Pluto which orbit beyond Neptune. With this new definition there are now two recognized plutoids: Pluto and Eris. Up until recently Eris was known as a trans-Neptunian object, so in a way it has been "promoted" to be in the same class as Pluto. So that means the solar system now has 8 recognized planets and 2 plutoids. Perhaps that is what the OP meant by two planets being discovered? It's not clear at this point what the IAU will call large objects that orbit inside the orbit of Neptune, such as Ceres.

See: Pluto Now Called a Plutoid - Yahoo! News (http://news.yahoo.com/s/space/20080611/sc_space/plutonowcalledaplutoid)

I only know one planet that was discovered, it is named UB313.

I only know one planet that was discovered, it is named UB313.

UB313 ISN'T a planet at all, but simply another dwarf.
Eris (dwarf planet) - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/UB313)

UB313 ISN'T a planet at all, but simply another dwarf.
Eris (dwarf planet) - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/UB313)

Seems that Wikipedia article is out of date - now that Eris is known as a plutoid.

Time to get editing then ;)