For a celestial body to be considered a planet, it must;
1) be in orbit around the sun.
Clearly, Pluto is in orbit around the sun, but so do thousands of asteroids.
2) have sufficient mass to assume hydrostatic equilibrium.
No planet is a perfect sphere. Due to their rotation, often they are a little squashed along the polar axis.
This criterion is just saying they that they must have sufficient gravity to have overcome other forces and mould a more-or-less sphere-shaped body. Pluto maintains hydrostatic equilibrium, whereas many of the asteroids and other minor planets are quite oddly shaped.
3) have cleared the neighborhood around its orbit.
This final criterion requires that it must have cleared its orbit of all other objects of comparable size, other than its own satellites. This means "a planet" must be gravitationally dominant in its orbit and this is where Pluto fails. Pluto not only shares its orbit with a number of other Kuiper Belt objects, but it also flies inside the orbit Neptune
So of this point Pluto is considered a dwarf planet even with its own moons and stuff
Hope this helps
