Poké Walker

The Poké Walker came out with Pokémon Soul Silver and Heart Gold.

Function
The Pokéwalker is used to walk with Pokémon in real life. To access the Pokéwalker, you need to find "CONNECT TO POKéWALKER".

Whenever you put a Pokémon in the Pokéwalker, it automatically levels up after one step, but it only levels up once every stroll.

For every 20 steps you take you get 1 Watt, which is the currency in the Pokéwalker.

Poké Radar
To use the Poké Radar you need 10 Watts for every use. It shows 6 patches of grass and one with a ! on it. Use the arrow buttons and the center buton to select the grass with a !. Once you select it, a battle will commence. Both Pokémon will have 4 HP. You will have three options: Attack, Evade, and Catch. Attack means that your Pokémon does 1 HP damage to the enemy. Evade is to evade your enemy's attack and attack back, but be careful because the enemy might run when you use it. Catch is throwing a Pokéball at the Pokémon and either capturing it or it runs away.

Dowsing
Dowsing is another option to use on the Pokéwalker. To use the Dowsing Machine, you need 3 Watts every use. There are some patches of grass in a line. You must guess which one has an item. If you don't get one, it will tell you if it's close or far away. If it's near, it is 1 grass away and if it's far it is 2 or more.