The earliest form of Rock-Paper-Scissors was mushi-ken. It originated in China, and is just like Rock-Paper-Scissors, but with a Frog, a Slug, and a Snake instead.
>Frog beats Slug
>Slug beats Snake
>Snake beats Frog
If they made a trio of Pokemon based on this concept, what would their types be?
>>27331440
Water grass fire
>>27331440
Froakie, Snivy, and Slugma fit the criteria
Poison Snake > Grass Frog > Ground Slug > Poison Snake
How does a slug beat a snake?
>>27331440
>Slug beats Snake
>>27331854
>Snakes swallow Toads in one gulp, Toads snag Slugs easily with their tongues, and Slugs dissolve Snakes with their mucus
...or so it is told in a Japanese tale. Which may or may not be based on the Chinese tale OP was referring to.