Heading north from Pallet Town, Trainers must make their way around a large but very primitive route, that will become their very first route they will explore on their journey. The route is riddled with large patches of tall grass, and ledges that contour from far east to all to the far west, blocking off most of the route making it hard to travel north, only to have small gaps by which the road has been broken into it.
From the narrow "gateway" into Route 1, the route will make its way west as a ledge will block the road, however patches of tall grass be found by traveling east. After traveling north past the gap in the ledge, there will be a small clearing, where a man working for a Poké Mart can be found giving out a free Potion to Trainers. Heading away from the small clearing, the route makes its way eastern, and creates an "S" shapes as it winds around tall ground, as well as long ledges. Route 1 then travels northerly through two consecutive patches of tall grass, one larger than the other. It then finishes off by curving westerly, and then north as it enters Viridian City.
Heading south from Viridian City, Trainers can either hop down ledges to completely avoid any contact with wild Pokémon on their way to Pallet Town or they can travel through the grass patches, the required path for northbound travel. Following the grass-lined path, the route turns east then south as it enters the first patch. After a small break, the path of the route enters another patch of grass as the route turns west. Route 1 then makes an "S", turning to the south, then to the east before returning south and west, passing through the third grassy area. The path then juts south, entering another patch before curving to the east then to the south as it enters Pallet.
There are no opponent Trainers on this route in Generations I and III. However, a man who works at the Poké Mart in Viridian City will give out a free sample of Potion to Trainers who talk to him. In Generation II, the Poké Mart employee has left and two Trainers appear instead, while in Generation IV four Trainers are on the route. A Bitter Berry grows here in Generation II, while a Blk Apricorn does so in Generation IV.
The route layout in Generations I and III are identical except for the fact that the Generation I version has grassy patches to both the east and the west of the route itself. The grass beyond the barrier was removed since in Generation I, Trainers could enter the grass using the walk anywhere glitch and, upon doing this, the game would freeze. This was because the grassy area contained no data for cities, routes, or even wild Pokémon, and the game would crash upon trying to retrieve the missing data.
Apart from this, most aesthetic features have been enhanced. Trees have become bigger, flowers are more visible, and most other sprites have been upgraded to Generation III standards.
The route remains mostly the same apart from a few minor changes to the gameplay. Heading south from Viridian City, Trainers can either hop down ledges to completely avoid any contact with wild Pokémon (which now include Sentret, Furret and Hoothoot) on their way to Pallet Town, or alternatively travel through the patches of grass.
On their way down, there are two other Trainers waiting for battle. One can found near the northern side of the route, while the other can be found in the near the middle in the clearing. He has replaced the ViridianPoké Mart employee who gives away Potions, however there is a Bitter Berry tree that sprouted along the northwest portion of the route. Lastly, the grass patches outside of the route have been removed but the spacing between the route and the surrounding forest still remains.
Other than graphical updates, the basic layout remains the same as previous generations, but the route is no longer flat, due to hills being added to give feeling of depth to the route. Heading south from Viridian City, a gate has been added between the route and Viridian City, in order for the game to load the different tilesets used between the areas.
The Bitter Berry tree has been changed into a Blk Apricorn tree, which can be found between the two ledges located on the northwestern side of the route. By traveling east, Trainers are able to battle a Schoolboy, and by jumping off the ledge and heading east, another Schoolboy can be challenged, with Pokémon similar to the other Schoolboy in Generation II.
By jumping down the ledge and going through the tall grass, the route soon turns into the clearing. Like in Generation II, the Viridian Poké Mart employee is no longer present and is replaced by a Trainer. However, a photographer is present on Mondays, Tuesdays, and Saturdays who will take a picture of the player and his or her party.
There is a male Ace Trainer just south of the photographer, as well as another female Ace Trainer, with Pokémon similar to the other Cooltrainer in Generation II. Route 1 makes the "S", turning to the south, then to the east before returning south and west, passing through the third grassy area. The path then juts south, entering another patch before curving to the east then to the south as it enters Pallet Town.
Route 1 was introduced in Pokémon - I Choose You!. Ash, who had just received his Pikachu and was still trying to get a handle on the rebellious Pokémon, set off on his journey, beginning with Route 1. He first found a Pidgey and was eager to catch it, but Pikachu didn't want to help him and instead ran up a tree. Frustrated, Ash decided to try to catch the Pidgey without Pikachu's help. He threw a Poké Ball at it, but the Pidgey broke out easily and fled. Ash turned and saw a Rattata digging through his bag.
Ash turned and saw a group of Pidgey in the field; he threw a rock at them, which only scared them away. However, he saw another bird Pokémon in the field, mistook it for another Pidgey, and threw another rock at it, which hit it in the back of its head. When it turned to look at him, however, he realized that he actually hit a Spearow. The Spearow swooped several times to attack him and Pikachu.
As the Spearow chased Ash and Pikachu, two herds of Pokémon that do not appear on this route in the games were seen: Mankey and Sandshrew.
After jumping in the river, narrowly evading an attack from a Magikarp and Gyarados, Ash and Pikachu met Misty, who was fishing for Water Pokémon. He stole her bike, putting the injured Pikachu in its basket, and rode away, promising that he would bring it back someday. They were attacked once again by the Spearow, but Pikachu used a massive electrical attack to take out the entire flock. Once the storm cleared, Ash and Pikachu both rose from where they were knocked back on the ground, exhausted but victorious. Ash looked up and saw an unknown Pokémon majestically flying through the sky, over the rainbow that had been left after the storm, but his Pokédex could not identify the species.
Route 1 appeared in File 1: Red, where Red was seen traveling through it on his way to Viridian City. Soon after entering the Route, he encountered a wild Pidgey, and tried to catch it, but it got away. After a short while, he got the hang of catching Pokémon, and caught multiple different species, including a Spearow, Caterpie, and Pidgey.
Along the way, he encountered a Youngster, who challenged him to a battle with his Nidoran♀. Not knowing other Trainer's Pokémon couldn't be caught, Red tried to throw a Poké Ball at Nidoran♀, only to have it bounce off. The Youngster, however, agreed to tell Red where he could find a Nidoran of his own. Shortly before arriving in Viridian City, Red encountered Blue, who challenged him to a battle. Due to Blue's Squirtle having a type advantage over Red's Charmander, Blue easily won the battle. Afterwards, Red met Brock, who, having watched the battle, suggested Red that he should start challenging the Gym Leaders in order to learn how to battle.