There is no objective criteria for what a planet is and isn’t
There are - exactly three.
- is in orbit around a star,
- has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
- has "cleared the neighbourhood" around its orbit.
The last one means that its gravitational pull has removed any smaller objects that might be in its orbit, either by kicking them out of it, or by catching them as moons.
Pluto's orbit is full of debris.