Which characteristic of bacteria permits them to develop antibiotic resistance?

Bacteria in a unicellular organism that has an archaic structure but is very smart, specifically in antibiotic resistance.
Bacteria have several characteristic or "weapons" to fight antibiotics:
Bacteria has a cell wall which do not allow toxic substances to go in.
Bacteria has transporters which expulse the antibiotic molecules that enter into the cell.
Bacteria has enzymes that break the antibiotic molecules and make them inactive
Bacteria can mutate (change) itself so, and by the way the antibiotic sites, so the molecules cannot fix it. And that is the most problematic.
Bacteria can transmit it resistance mechanism to other bacteria, even if they are not from the same family.