Route 23 (Japanese: 23ばんどうろ Route 23) is a north-south route located in northwest Kanto. In every generation it appears, the northern terminus is at the entrance to the Pokémon League at the Indigo Plateau. In Generations I and III, Route 23 is a lengthy route separated into two segments by Victory Road and terminates at Route 22. In Generation II, Route 23 is virtually non-existent and serves as a connector between Victory Road and the Indigo Plateau, terminating less than 15 paces from its northern terminus.
It is one of the last stops on the way to Indigo Plateau's Pokémon League. Trainers will need Badges to progress further along Route 23 in Generations I and III. Upon collecting all eight from the eight Kanto Gym Leaders, trainers will be able to walk to the north end of Route 23 and enter Victory Road.
In Generation IV, the area is simply named as part of the Indigo Plateau, causing Route 23 in and of itself to no longer truly exist, though a header for the area for the Pokémon status screen is found in the games' code.
Southern segment
Heading north from the Pokémon League building, which houses the first badge checkpoint, Route 23 heads northeast, passing through the first of many archways on the route as well as the second checkpoint. Northwest of this point is the second archway and the third checkpoint. The main path of the road then heads north, taking a slight northeast alignment as it approaches the third archway and the fourth checkpoint on the bank of a waterway that effectively separates the route into two halves.
Directly north of the fourth checkpoint is checkpoint five, in the shadow of archway four. Northeast of this location, past an island in the water that splits the channel into two, is the next archway/checkpoint. The route continues north, making landfall northeast of the sixth checkpoint.
In this area, Route 23 is dotted with grassy patches and boulders, creating a unique look not seen anywhere else in Kanto outside the Safari Zone. North of the scenery, the route encounters the seventh checkpoint underneath the final archway on the route.
Route 23 turns to the northwest, passing the final patch of grass on the road before returning to a north-south alignment several paces south of the final checkpoint. Just north of the checkpoint is the south entrance to Victory Road.
This segment doesn't exist in Generation II and IV.
Northern segment
The route heads north from Victory Road's northern portal, arriving at a series of stones intended to create a maze. On the other side of the maze, Route 23 ascends a series of stairs before arriving at the front door to the Indigo Plateau.
This segment exists in all generations that Route 23 exists(Generation I to III), but the maze doesn't exist in Generation II.
Only minor cosmetic differences exist between Generations I and III.
In Generation II, Route 23 was reduced to an extremely short path connecting the front door of the Indigo Plateau with the northern portal of Victory Road. No items of interest were placed on the route; in fact, the route itself is completely barren with the exception of the surrounding scenery that makes up the border of the route.
In Generation IV, the route is named as part of Indigo Plateau, and thus does not technically exist as a visitable location, though the location data does exist in the game. The connection with Route 22 is now made on the south side of Victory Road, which leads directly into the Pokémon League Reception Gate, linking the cave with Route 22, Route 26 and Route 28.
The reason of why Route 23 disappeared in Generation IV or is shrinked into an extremely short road in Generation II is probably because Pokemon League Reception Gate replaced all badge checkpoints on this route and the route has no purpose other than being badge checkpoints.