Lately I've haven't been able to look into Oddish a bit, Besides the movesets, What makes Oddish a poison type. Grass I understand. Poison...explanation?
Explaination:
Oddish can be seen as a parallel to Bellsprout. Both are Grass/Poison-type Generation I Pokémon, part of a three-stage evolutionary line, can evolve starting at level 21, and whose second evolutionary event utilizes a Leaf Stone. Oddish is exclusive to Pokémon Red and FireRed, while Bellsprout is exclusive to Blue and LeafGreen, with both Pokémon found in the same locations in their respective versions. Additionally, both can be found at White Forest in White, and both Pokémon have had their Egg designs revealed. Because Bellsprout is a Grass/Poison Type?
Oddish is based on Mamdrake.
All species of Mandragora contain highly biologically active alkaloids, tropane alkaloids in particular. The alkaloids make the plant, in particular the root and leaves, poisonous, via anticholinergic, hallucinogenic, and hypnotic effects. Anticholinergic properties can lead to asphyxiation. Accidental poisoning is not uncommon. Ingesting mandrake root is likely to have other adverse effects such as vomiting and diarrhea. The alkaloid concentration varies between plant samples. Clinical reports of the effects of consumption of Mediterranean mandrake include severe symptoms similar to those of atropine poisoning, including blurred vision, dilation of the pupils (mydriasis), dryness of the mouth, difficulty in urinating, dizziness, headache, vomiting, blushing and a rapid heart rate (tachycardia). Hyperactivity and hallucinations also occurred in the majority of patients.
Nuff said