DID YOU KNOW? WHEN THE TOCHUKASO FUNGI GREW PARAS, IT BECAMES PARASECT.
The Tochukaso fungi is in fact a parasite, siphoning nutrients from Paras until it matures then take over hence, the Paras' pupil is gone when it became Parasect.
Removing the mushroom will stop Parasect from moving (severed nerves).
Although it controls it's prey, the Tochukaso greatly improves Paras' base stats.
Tochukaso is the Japanese name of the real world fungus Ophiocordyceps sinensis which ultimately controls the host.