Planet classes that should not exist (but can)

Back on the planet types. Like the types that should not be possible.
Examples are Chlorine-rich atmosphere or even fluoride-rich atmosphere.

So, what if they do exist? These chemicals are likely to combine with other chemicals, thus preventing free fluoride or chlorine in the atmosphere. But, the same could be said for oxygen.
That's right, maybe these planets exist with these atmosphere, cause primitive life did it the same as freeing the oxygen in Earth's atmosphere.

Anyhow, I was wanting to know what types of atmospheric chemicals we can come up with that should, technically, not form naturally.
The idea was from the thought that Earth may actually be a carbon-rich atmosphere Earth.
Cause, it is assumed that microbes freed up the oxygen. And also, the large deposit of oil (and other hydrocarbons) that if burned, would be enough to make a significant amount in the atmosphere to be considered carbon-rich atmosphere.
I can not find the hypothesis on this, but I remember reading it from somewhere.


Atmospheric Types that are likely caused by microbes:
0) Oxygen-rich? As in dioxygen, ozone, and free oxygen.
1) Chlorine-rich, on a planet that is before the snow-line.
2) Fluorine-rich.
3) Sulfur-rich gas species? (can someone verify this. Large amounts of sulfur in the atmosphere of a non-volcanic active world)
4) Hydrogensulfide-rich as a gas? (considering that the boiling point is at -60.28 °C (212.87 K), wiki)
5) Methane-rich on hot worlds? (considering that methane is destroyed by sunlight, a planet rich with it in a closer orbit)
#) Rarer gas that are dominant on other worlds?

Pure oxygen atmospheres are found in the outer three Galilean moons. Their source is the photodissociation of water ice via sunlight.

It's a big universe. Its smart to keep an open mind

Then, I guess an oxygen-rich atmosphere on cold words?

Also, I was mistaken, it was a carbon-rich atmosphere. Not a carbon-planet Earth.