Realistic Shedinja

Copy pasta from my previous work:

Nincadas who fail to develop through the last stages of their metamorphosis (due to lack of nutrition, and proper environment condition) often times become prey to a rare species of cordyceps. The discoloration from grey to beige signifies the activity of the parasite as it tries to overtake the Nincada. It starts at the back area, crawling through wings and the legs. As soon as the cordyceps takes over the majority of the body, other useless parts starts to crumble such as the eyes and the hind legs. Reaching the final stages of parasitism, the last remaining parts of the brain mutates with the cordyceps rather than becoming consumed by it. Part of the mutation is the growth of new halo-like appendages coming out of its former antennae, functioning as super sensitive scent detectors. The mutation results to a new species of pokemon called Shedinja. 

Shedinjas, in contrast to their successfully morphed brothers, are slow, and timid. They have virtually no predator, thanks to their halos that contentiously emits a chemical that changes the chemistry of their environment, causing potential predators nausea and sudden decrease in appetite.