The first thing you should do is heal up at the Pokemon Center, which is the building closest to the entrance of the town. Each town has a Pokemon Center that heals all of your Pokemon completely for free!
With your Pokemon in top shape, go to the Poke Mart to the northeast. This building usually sells various items for Pokemon. The clerk will ask you to take a parcel back to Pallet Town to Professor Oak the first time you come in. You’ll have to quickly return to Pallet Town and deliver the package before you can buy any items.
Deliver the Package
The quickest way to return to Pallet Town is by jumping over the ledges on Route 1. Enter Professor Oak’s Lab to deliver the package. He will then give you and your Rival a Pokedex! This is an item that automatically lists all the Pokemon you have seen and captured.
Before you return to Viridian City, you can visit your Rival’s sister in the house to the northeast. She will give you the Town Map item, which will help you around Kanto if you get lost. Of course, this guide will also help you!
Return to Viridian City
Now that you have delivered the package and received your Pokedex, you can buy some items at the Poke Mart. The first thing you need are Poke Balls to capture wild Pokemon. You should also buy some Potions to heal your Pokemon when far away from a Pokemon Center. If you’re playing Pokemon Red, I recommend getting a few Antidotes to cure Poison.
The leader of the Pokemon Gym will not be in at this time, which means you need to go north to the next town. Before doing so, quickly head west to Route 22 and prepare for a Pokemon battle.