A pollutant is something that upsets the natural balance, and you have raised two or three separate issues here:
1. CO2 is a naturally occuring component of the atmosphere, but too much in the atmosphere is thought to contribute to global warming, hence CO2 emissions are seen as a pollutant.
2. Ozone is an oxygen molecule, O3, that is created naturally in the upper atmosphere and forms the ozone layer which helps to block harmful UV rays from the sun, so a hole in the ozone layer could be a problem. It was supposed that man-made chemicals such as CFCs were making the hole larger, but I think it has improved more quickly than was expected since CFCs were banned.
3. Ozone at ground level is the result of man-made pollution such as car exhausts, and this is what causes smog.
These issues are quite complex, but it is important to understand the basic science behind them if we want to do our best to protect our planet and the life on it. I have heard both sides of the story concerning global warming, my science degree taught me that it was man-made, but I have also listened to some more radical thinkers who believe it is all a concoction of big businesses to manipulate the markets regarding oil prices etc. and that global warming is happening because of natural cycles, sunspots etc.
Whatever you believe, it is in all our best interests to cut down on pollution wherever we can and look after the environment that we depend upon for our existence.