Kanto is old news. But with a little work, it could be new again. Building on how Sun and Moon moved away from the linear town-route-town map structure, I imagine a more open-world kind of map with zones a la Final Fantasy XII. I based the design of this on that game's world map. As an additional bit of inspiration, I designed the layout to more closely resemble the layout of the real life Kanto region of Japan, positioning locations geosynchronously to their IRL counterparts where possible and even designating prefectures amalgamated from the real ones. Thoughts?

Viridian Prefecture (Shizuoka and Yamanashi prefectures, which amusingly aren't even in IRL Kanto)
>Pallet Town (Shimoda)
>Viridian City (Hakone)
>Viridian Forest (Chichibu National Park)
>Indigo Plateau (Kofu)
>Mt. Silver (Mt. Fuji)

Pewter Prefecture (Nagano and Gunma prefectures)
>Pewter City (Maebashi)
>Alabaster City (Nagano City)
>Alabaster Quarry (Kusatsu)

Cerulean Prefecture (Tochigi and Ibaraki prefectures)
>Ochre Town (Utsunomiya)
>Mt. Moon (Mt. Akagi)
>Cerulean City (Tsuchiura)
>Cerulean Cave (Mt. Tsukaba)
>Cobalt Town (Mito)

Fuschia Prefecture (Chiba prefecture)
>Lavender Town (Narita)
>Vermilion City (Chiba City; supposedly Yokohama but lol geography)
>Fuschia City (Tateyama)

Saffron Prefecture (Tokyo, Saitama and Kanagawa prefectures)
>Saffron City (Tokyo City)
>Celadon City (Saitama City; supposedly Shibuya)
>Amaranth City (Yokohama)
>Tritone Undeground (Tokyo subway system)
>Cinnabar Island (Oshima)