Stownidae

After curling into a ball, it evolves into Stownidae. This Pokémon is around the size of a large rock. Its arms and feet degrade into smaller limbs it uses to just crawl when it rarely has to do so. Its body is filled with venomous spikes which cause immediate severe, blinding pain to the person who got stung. Within minutes, the spot swells and becomes red, spreading through the limb. In under an hour, it can cause breathing issues, paralysis, shock, and for many individuals death. If left untreated, it can result in heart failure within hours. Luckily, an antidote for this specific venom was successfully developed, and is commonly administered. Although the spray itself is enough to buy you time, it's still advised to go to a hospital as to ensure you're fine. Its eyes are wide and hollow, its mouth has razor sharp teeth it uses to chew on hard things, and its dorsal fin is almost useless in this stage. Interestingly, results showed that if you'd drop one into water, it would just move to the sea floor where it would use its rocky body to act as a safe spot for fish. It then eats them.