SS Monothreat
Monothreat is the moniker for a Monotype format when two players intentionally bring the same type against each other. Given that both players are using the same type, they can build around very specific threats and run Pokémon that counter their own type. Essentially, you can think of it as regular Monotype, but both players agree to bring the same type beforehand. The premise is quite simple, but the amount of innovation and trickery involved is not.
Each Monothreat type forms a metagame within itself, so the format can be daunting to begin playing. Due to how teams are built, it is common to see Pokémon in Monothreat that you would otherwise not see in regular Monotype, such as Tsareena on Grass or Galarian Rapidash on Fairy. Building for Monothreat tests the boundaries of a Pokémon's movepool and rewards Pokémon that can fulfil a particular niche, even if it is otherwise subpar in regular formats. An example is Tauros, which is A rank in Monothreat but unranked in Monotype because it is the fastest Normal-type that has Close Combat and a relatively high Attack. Ultimately, Monothreat revolves around creative problem solving and resourcefulness to gain an advantage against your opponent because, as many players say, a Monothreat game can be won or lost in the teambuilder, so being detailed-oriented is key!
On the whole, I feel divided about what generation this would be best in. SS brought many new prominent Pokémon, items, and mechanics that differentiate it from SM, but, arguably, we lost just as much, if not more, along the way. Monotype was hit hard by the loss of certain threats and mechanics, but Monothreat specifically feeds off a plethora of Pokémon options and their movepools to respond to centralizing threats through creative avenues. For SS, it is the most popular generation at the moment and the playerbase is relatively more into SS than SM or even NatDex.
NatDex in itself has a lot of arguments and notable benefits. Pokémon and moves that are not transferrable between SM and SS would only benefit the metagame because a lot of important Pokémon play significant roles that aren't fulfilled by any other Pokémon. Nearly every type in SM had an S-ranked Mega Evolution, further epitomising their impact and usability.
The loss of moves also plays an important role because Monothreat feeds off movepool depth and versatility. Hidden Power single-handedly keeps Pokémon such as Ferrothorn and Scizor, two notable SS defensive walls in Grass and Bug, respectively, at bay. Even lesser-seen moves such as Signal Beam will only strengthen the possibilities available. When two same types are facing each other, it becomes crucial to have coverage to hit the opponent as hard as possible.
Regular Monotype rules would apply. To decide a type beforehand, players would either converse through wall posts or by commenting on the tournament threat. Each player would have to list three of their preferable types, which would make the process of choosing a type smooth.
