>>57293887For the other half of Tokyo, there's Yamabuki City (Saffron). Yamabuki is a type of flower, being a bright yellow/gold, hence the name Gold Badge. In the Dragon Ball manga, Goku's outfit is said to be "yamabuki color". Gold also sounds quite premium, and there's a reason for that beyond the city being Tokyo. You may have noticed that Saffron City is the final indexed flight location after all other locations. During development, Gen I had a different set of badges, with the final badge being the Gold Badge obtained in Saffron. There was also a planned facility with multiple floors, each floor containing a group of Trainer types you had to battle (including every Gym Leader and Elite Four) in a gauntlet. Each floor had different wild Pokémon, with the final one having wild Mewtwo.
The name and design of the Gold Badge, beyond simply sounding really premium, refer to a Japanese fad in the 80s where people would buy gold circle stickers that would supposedly unlock their latent psychic powers, hence the connection to Psychic-types and why Sabrina is relatively overpowered compared to all other Gym Leaders.
One more bit of trivia. Tokiwa City (Viridian) comes from another name for evergreen trees, being a verdant green, hence the name Green Badge. Giovanni's Japanese name is Sakaki, a type of evergreen tree with religious significance to Shintoism, and the appearance of the branches resembles the Green Badge. In Gen II, the rival (whose Japanese name is Green) becomes the Gym Leader and gives out the badge matching his name.