pokemon-showdown

Pokémon Showdown is a free, browser-based Pokémon battle simulator that allows players to build teams and compete in real-time battles using any Pokémon from any generation. It is designed for competitive players and fans who want to test strategies without needing to train in the main games, offering a fast, accessible, and deeply customizable experience. Its interest lies in its massive community, automated tiering system, and role as the de facto standard for competitive Pokémon theorycrafting and play.