Gastly

Gastly is a Ghost- and Poison-type Pokemon composed almost entirely of toxic gas held loosely together around a dark, hovering orb. It is one of the most ephemeral Pokemon on the island, capable of passing through solid objects, and tends to dissolve at the edges in a way that makes it look less like a creature than a rumour that has learned to move.

Settlers who build with any degree of atmospheric intention will find Gastly appearing reliably and early, a welcoming sign that their island already has a personality.. On Pokopia Island, Gastly is one of the most accessible Ghost-type visitors, appearing in any environment that has even a modest atmospheric quality. Stone Lanterns, dark corners, Gothic Garden features, and spaces with dim or mood-focused lighting are sufficient to draw it, making it an early reward for settlers who put any thought at all into creating an interesting atmosphere. It drifts through walls and fences without apparent awareness of their existence, which can be disconcerting at first but becomes one of the island's more entertaining ambient features