There is little to do in Pewter City beside healing up at the Pokémon Center. The Poké Mart does contain one new item.
Poké Balls - P200, it's always a good idea to stock up on these.
Antidotes - P150
Awakenings - P250, these will heal the Sleep status ailment. It would not be a bad idea to pick up one or two.
Burn Heals - P250
Parlyz Heals - P200
Potions - P300
Escape Ropes - P550, these items can be used outside of battle and will return you to the doorstep of the last Pokémon Center you used. Their best use is when you are deep in a cave with low health. Note that they are frequently found inside such caves for free.
If you want to brush up on your history, head into the Pewter Museum of Science, to the north; however, this is not required for anything and costs P50. When you're finished exploring. Enter the gym.
Now that your ability to get free stuff is no longer in jeopardy, I will go over the Pokémon Mart stock in Viridian City. You can buy:
Poké Balls - P200, I recommend stocking up on these, because many Pokémon can be caught in the next few areas.
Antidotes - P100, these will heal the Poisonstatus ailment; however, many of them can be found for free.
Burn Heal - P250, these will heal the Burn status ailment, but you will not encounter this ailment for quite some time, at which point better items will be available.
Parlyz Heal - P200, these will heal the Paralysis status ailment, but you won't encounter this for a while either.
After restocking, head back to Route 22 to catch some more Pokémon.
The first thing to do upon entering any town is to head to the Pokémon Center, where the nurse will heal your Pokémon for free. This restores their HP, PP and status. In the northeast corner of the Center is a PC. Not only can this one store items, but it can store Pokémon as well, up to 240 of them. If you have access to another Game Boy with Red or Blue Version and a link cable, you can battle or trade with them by talking to the attendant on the right. After finishing up at the Center. Head northeast to the Pokémon Mart. Upon entering, the clerk will identify you as being from Pallet Town, and give you Oak's Parcel, which you need to deliver to him. You can't buy anything until you do, so exit. One more thing you can do here is walk clockwise around the clump of trees in the northwest part of town. Examining the cuttable tree with A will yield a hidden Potion. Next, head back to Pallet Town.
Welcome to Route 1, the first place in the game where you can encounter wild Pokémon. They are as follows.
Pidgey
Normal/Flying
L2-5
50%
Rattata
Normal
L2-4
50%
If you talk to the first person you run into, you will learn that he is a Pokémon Mart employee and he will give you another free Potion. You can't catch Pokémon for now so continue heading north until you reach Viridian City.
