How did Skill "survive"? On the last episode of Re:_Hamatora, Art killed his brother Skill to free him from his pain. Then, Skill dies(?) and Art is unconscious. Moral appears and checks Skill for vital signs but discovers that he has died.

However, in the last fight between Nice and Art, Skill is shown still alive.

How did Skill "survive"?
Moral proclaimed that Skill was brain dead, but the Minimum Root was actually the heart of Skill*, which was still intact. This heart was most likely transplanted into Nice by Moral**. So Skill is thus "still alive" through living on through the heart of Nice/Skill.

You also have the hesitation line by Art who could not yet kill his brother, since he does know that Nice's Heart is actually Skill's Heart.

This also explains how Art survived his fall as Nice/Skill probably restored his Minimum during the fall.

*Notice how Art's Minimum Root is also his heart too

**This also explains how Nice was able to save the gunshot wound, implied that it shot his heart