I will not object to everything.Why's it not logical? Moons have gravitational pulls as well. And some moons are larger than the planet Mercury. Jupiter's moon Ganymede and Saturn's moon Titan are both larger than Mercury.
And Pluto isn't a moon.
At the moment, there are no known moons with moons, but it is possible. It is thought that Saturn's moon Iapetus may once have had a moon.