A Pokedex visualization uses a Sankey diagram to map Pokémon types to their legendary counterparts, showing which types lead to the most powerful creatures. The flow diagram connects type nodes like Water, Dragon, and Flying to specific Pokémon such as Kyogre, Rayquaza, and Lugia. Built with D3.js v3, the example implements a custom `d3.sankey` layout to calculate node positions and link depths, rendering the diagram as SVG with interactive hover effects on links. The data comes from a JSON file containing typed links and node values.