Last night, while I was absentmindedly browsing Bulbapedia and reading information about Pokémon variants, when I stumbled across an article about Pokémon XD: Gale of Darkness's purification device. From what I read, it was powered by a ring of four Pokémon, each positioned so that their typing formed a super-effective matchup with the next in clockwise order. This inspired me to make this puzzle. I initially tried a more complex design for this puzzle with 10 nodes, only to spend an hour puzzling over it before realizing that it was likely impossible. So I settled for this simplified design, which I was able to find a solution for within ten minutes. The rules are simple: without using any more than once, put a type in each node so that all the arrows indicate a super-effective relationship between the types.
Download a vector version of this puzzle: https://assets.scratch.mit.edu/363ff48d031c9d742dfb06affb79a906.svg
