Paras is born with tiny spores covering their body, which grow into tochukaso mushrooms as the Pokémon feeds. It is noted in that the relationship between the host and the mushrooms is a symbiotic relationship: the mushrooms will sap energy from the host, causing the Paras to continuously burrow underground in forest areas to gnaw on tree roots, since the tochukaso draws most of the energy from the roots. In return, the mushrooms defend the host by spraying toxic spores at enemies. The mushrooms themselves have strong healing properties, and are valued for their life extending properties.

Is a basic parasite-like Pokémon that has two mushrooms on its back. Paras can be found in some caves and the Safari Zone in Kanto and in Ilex Forest and the Bug Catching Contest in Johto.