ekans and arbok

Certainly!

Ekans
The Snake Pokémon
Type: Poison
Official Registration #: 23
Entry: An ekans develops its venom as it grows. This means that the venom of a young ekans is not as potent as the venom of an older ekans, and newborn ekans lack venom entirely, although their bites are still painful. When determining the age of your ekans, always judge by the length, not by whether or not it possesses venom; the longer the ekans, the older the specimen. Allowing an ekans to bite you in order to determine whether or not it possesses venom is not only a reckless idea but also the cause of death of many early Kantonian settlers.

Arbok
The Cobra Pokémon
Type: Poison
Official Registration #: 24
Entry: The evolved form of ekans, by battle experience. It is said that the elaborate patterns on its belly vary from area to area. Unlike most rumors concerning pokémon, this is true. Arbok from different regions have adapted different patterns, based on what its prey would find most intimidating. For example, Japanese arbok possess terrifying but simple markings that resemble noh masks. European arbok possess markings that resemble the faces of dragons or local monsters. American arbok, meanwhile, possess markings that resemble the most terrifying faces of all: clowns.