Monarch Singleton is a Pokémon TCG format centered around building a 60-card singleton deck from cards released in Expanded-legal sets.
Bans are used sparingly, prefering to give overpowered cards a point value instead. Your deck cannot contain more than 4 points' worth of cards. (Your deck may contain one 4 point card, two 2 different point cards, four different 1 point cards, etc...)
This format is still in an early experimental phase and is a work in progress. This ruleset was written by a very casual Pokémon TCG player who hasn't played seriously since the original Team Rocket set in 2000. The points list was lifted wholesale from another format with a larger card pool and no singleton restriction as a starting point, but as more playtesting occurs, it will likely change significantly.
For the moment, please do not buy cards specifically with the intent of playing this format. While the intent is to make the format a stable, welcoming home for cards that have rotated out of Standard, mistakes and missteps are inevitable as we figure out what works and what doesn't. In the meantime: use your existing collections, proxy cards, use online simulators, and help us playtest and make this something cool.
My format balance and playtesting notes are publicly visible here.
In TCGs, traditionally a singleton format is one in which only one card with a given name can be in your deck at a time. Because the same name is repeated across functionally unique cards in the Pokémon TCG, the singleton rule must be clarified:
None from Expanded-legal sets.
Monarch Singleton is directly inspired by the Canadian Highlander format from Magic the Gathering, as well as the 殿堂 (Hall of Fame) format played in Japan.
The original version of the points list was the points list from the ババロコ殿堂 (Babaloco Hall of Fame) format, a variant on the Hall of Fame format played at the バトロコ (Batoloco) card shop in Takadanobaba, Tokyo. Only cards from Expanded-legal sets in this list were taken into consideration. Changes have been made to the points list since then.
Babaloco Hall of Fame is a casual derivative of the officially sanctioned Hall of Fame format born out of frustration with how little attention it is getting from The Pokémon Company, which points newer cards more aggressively. As a non-sanctioned format, Batoloco encourages the use of proxies for older, hard-to-find cards, and the store has a number of loaner decks available to encourage people to play the format. It's real cool!
U150 is a long-running singleton format for the PTCG with small but devoted player communities around the world. They use the Unlimited card pool and approach balancing and consistency through sweeping errata and rules changes. This can be confusing to less experienced players, and can be hard or impossible to enforce in various online clients. They have dealt with many of the same balancing issues we have to deal with, and while we may not always agree with the way they chose to resolve them, their work is incredibly helpful in helping us decide what to do for our format.