Pokémon HeartGold and SoulSilver/Goldenrod City

Get a free bike
Sensing that you're a guy (or gal) who gets around, the manager of the Bike Shop (lower right corner of the city) will offer you a free bicycle if you promise to advertise his shop by riding around. When you wander into the Bike Shop, the owner will ask you to ride around on one of his bikes to show everyone how much fun it is. You can move much faster with the bike. You can register the bike by selecting it in your Pack, then choosing SEL from the menu. After that, just hit Select when you want to ride.

Bill's house
Bill's home is here in Goldenrod City (the leftmost house in the southern portion). He's currently away in Ecruteak City, but his mom and sister are home. If you drop by to visit his family, Bill's sister will give you his phone number, which you can use to check how full your current box is at any time. Even if you don't get his number, he will call you if you fill up a box when catching a new Pokémon.

Bill will head back home after you meet him in Ecruteak City, and if you come back to his house afterwards, he'll have a very nice surprise waiting for you. If you'd like to know what that is, please see the Ecruteak City page.

Name rater
A name rater lives in Goldenrod City. If a witty name for a favorite Pokémon has finally occurred to you, come to the guy who lives to the left of the Gym and he will rate the name of a Pokémon in your party (your choice). He will give you the option of changing that Pokémon's name. Unfortunately, he won't let you change the names of Pokémon you received from other players or in-game traders.

The Happiness Lady
Certain Pokémon now evolve based on the hidden stat "Happiness". If you want to check how happy a Pokémon is, put it in your top slot and talk to the woman in the house above the Bike Shop. She'll tell you what your Pokémon thinks of you, so you know how much you need to spoil it.

Get the Squirtbottle
The woman in the small house in the Northeast corner of Goldenrod will give you information about the living tree blocking the way to Route #36. In Gold and Silver, after you beat Whitney, the Goldenrod City Gym Leader, go back to the house and she will give you a free Squirtbottle to use to bother the tree. But it's a little more difficult in Crystal. You'll have to head northeast, cutting through Route #35, and find the woman's daughter standing by the tree on Route #36. Follow her home and mom will give you the Squirtbottle you need to proceed.

Trade Drowzee for Machop
On the fifth floor of the Goldenrod Department Store, you can do trade your Drowzee for a Machop with the man in the left corner at the settees.