Gen 9 National Dex Monotype is a Smogon format that combines two rulesets: the Monotype restriction (every Pokémon must share at least one type) and the National Dex pool (every Pokémon ever released, including Mega Evolutions and Z-Moves). It uses Gen 9 mechanics including Terastallization. The format has its own banlist maintained by Smogon's National Dex Monotype council.
Dragon, Steel, and Fairy types gain the most from the expanded Pokédex. Dragon gets Mega Salamence, Mega Garchomp, and Mega Latios. Steel gains Mega Metagross and Mega Scizor. Fairy gains Mega Gardevoir and Mega Mawile. Water also benefits significantly with Mega Gyarados, Mega Swampert, and Primal Kyogre (if not banned). Ghost and Psychic types also have new options with Mega Gengar and Mega Alakazam.
National Dex Monotype gives access to Mega Evolutions, Z-Moves, and every Pokémon from past generations that isn't in the Scarlet and Violet Pokédex. This expands the pool for every type and introduces Mega Evolution as a core team-building element. Many types that are weak in standard Monotype become much stronger with access to powerful past-gen options or Mega Evolutions.
National Dex Monotype bans Pokémon deemed too centralising for the type-restricted format, plus standard Smogon clauses. Some Mega Evolutions and Pokémon that are too powerful within a given type are banned by the National Dex Monotype council. The current banlist is posted on the Smogon National Dex Monotype forum.
Start by choosing a type, then identify the best Mega Evolution available for that type — it will typically anchor your team. Fill the remaining slots with a mix of offensive threats, hazard setters, hazard removal, and defensive support. Dual-type Pokémon are especially valuable as they can cover your type's common weaknesses. Browse the teams on this page to see current archetypes.
Click any team card to open it, then hit the copy button. Open Pokémon Showdown, go to the Teambuilder, click "Import from text", paste the team, and save. Select Gen 9 National Dex Monotype as the format.
This page shows National Dex Monotype teams shared on crob.at. Official sample teams and type-by-type viability rankings are posted on the Smogon National Dex Monotype forum. The Pokémon Showdown Teambuilder also includes curated samples under the Gen 9 National Dex Monotype format.