Taking this discussion a step further: in the bullets/deer instance, you'd be more likely to evolve a primary lifeform that looked more like a tree or grass or slime-mold than a deer. That is, it either consists almost entirely of bullet-stopping material (wood), or is so lightweight that bullets don't effectively transfer energy to it (grass), or the structure is entirely decentralised such that a bullet, or even a hail of bullets, cannot disrubt the systemic function of the organism -- it simply absorbs the projectiles and functions around them.

A chlorine adaptation, if possible, would be along similar but chemical lines -- you'd end up with a non-protein based chemistry, or something not affected by chlorine, or which could buffer it to extreme levels.

Differential resistance to bleach at low concentrations might be possible to breed for. That could be interesting. In a similarly horrifying sort of way.