After earning all eight badges, you will be able to pass through all the gates throughout Route 23. Head west of Viridian City into Route 22. Your Rival will be stop you and challenge you to a Pokemon Battle.
Defeat your Rival to receive P8,160. Your Rival will run ahead after the battle. You can return to the Pokemon Center in Viridian City to heal your team if needed. When you’re ready, walk into Route 23.
Eight different guards will stop you along Route 23 to check your eight Pokemon League Gym Badges. You will also be able to capture wild Pokemon in the grass and water while traveling through the route. 3 Golden Razz Berries can be grabbed to the east near the start of the route.
A pack of 3 Golden Nanab Berries can be found on the east side of the route directly after your Thunder Badge is checked.
A pack of 3 Golden Pinap Berries can be found on the west side of the route after your Rainbow Badge is checked. You will have to sea skim to get it.
A pack of 5 Golden Razz Berries can be found on a small island after your Soul Badge is checked.
A pack of 5 Golden Nanab Berries can be found on the east side of the route in some tall grass after the small sea route.
A pack of 5 Golden Pinap Berries can be found in the tall grass after your Volcano Badge is checked.
After your Earth Badge is checked, you can enter Victory Road. This cave has many tough trainers and wild Pokemon. Make sure your Pokemon are strong enough to get through and you are stocked up on items.