Darwin is a mutant with an extremely malleable physiology, including:

Instantaneous Adaptation: Darwin's powers of self-protection offers continuous circumstantial evolution. Darwin is able to adapt to any situation. His reactive mutation adjusts his capabilities to his environment. Examples of such manifestations include receiving functioning gills after being submerged in water, gaining night vision after being in the dark for several seconds, being able to survive without oxygen when in space, his skin becoming fireproof when it is exposed to flames, his body becoming pure energy, his intelligence increasing itself or the understanding of the Shi'ar language by looking at it in written form. However, his powers do not always take the effect he desires. For example, during his fight with the Hulk, his body teleports him away from the battle rather than supplying a power that would allow him to defeat the Hulk.

Immortality or Near Immortality: As a byproduct of Darwin's continuous evolution, he may in fact be immortal. He can survive indefinitely in harsh conditions and/or without water or nourishment. Darwin even survived Hela's death touch.

Proactive Adaptation: After his battle with Hela, Darwin became able to trigger mutation that proactively ensure his survival sometimes by affecting others.