Pokémon Showdown is a Pokémon battle simulator where over 10 million battles take place each month. Pokémon Showdown is home to over a million monthly active users and provides a large number of chatrooms where thousands of Pokémon fans discuss their shared interests. Pokémon Showdown has been around for 8 years, and when it first launched it was revolutionary among battle simulators for being fully animated and accessible through users' web browsers. Pokémon Showdown is by far the largest Pokémon battle simulator in use today, with its unique 'Random Battle' format where players face off using randomly generated teams drawing in players of all skill levels. Pokémon Showdown was created and is still led by @Zarel, and its code currently exists across two repositories - server and client. Much of the foundational code used by other projects resides in the server repository, and Pokémon Showdown is the largest and most mature project the Smogon Develoment team works on.
Smogon is the most comprehensive and accurate online resource for competitive Pokémon battling. Smogon offers articles and advice via its community forums to help fans of the game compete at every level, while honing their skills in every aspect of competitive Pokémon from team building to battling tactics. The Smogon Dex not only contains exhaustive details about Pokemon abilities, items, moves, species, movepools and stats, it also provides information about the best strategies for using each Pokemon in each of the game formats where is it viable. The various analyses the Dex contains are contributed by the community, and the moveset information from the Dex is used by players during team building for battles on Pokémon Showdown or as input to the Damage Calculator. @chaos is the creator and lead of the Smogon Dex, which can be found in the smogon/dex repository.
The Damage Calculator provides additional information for Pokémon players to use during battles or team building and performs important calculations which are helpful to a player's decision making process. The calculator's main feature is to determine the amount of damage one Pokémon may inflict on another given a configured set of battle conditions, though the calculator also can be used to compute information about a Pokémon's 'stats' or outline common moveset configurations / options. The Damage Calculator combines logic about Pokémon's game mechanics with information from the Smogon Dex and from usage statistics to give players a better picture of how they might handle situations that occur during a battle. The original version of the calculator was created by Honko and featured revolutionary 'one-vs-all' and 'all-vs-one' modes for performing calcuations regarding multiple pokemon at once - it is now led by @Austin, and lives in the smogon/damage-calc repository.