Things You'll Need
Instructions
Unlock ̶0;Beyond the Sea̶1;
Travel to the Global Trade Station in Goldenrod City in your ̶0;Pokemon̶1; game. This building allows you to connect with other Pokemon players across the world and trade Pokemon.
Talk to the lady behind the counter. She will direct you to a room where you can trade your Pokemon.
Trade any of your Pokemon for any Pokemon from another country. Look for Pokemon named with Japanese letters, which usually indicates that Pokemon is from another country. Once the trade is complete, this will unlock the ̶0;Beyond the Sea̶1; route on your Pokewalker.
Catch Horsea
Transfer a Pokemon from your Nintendo DS game to the Pokewalker. This Pokemon should be at least level 15.
Select ̶0;Beyond the Sea̶1; as the walking route during the transfer.
Walk 2,500 steps or more, allowing the pedometer to detect your activity. You can see the number of registered steps in the bottom right corner of your Pokewalker. The Horsea will only appear after you have walked at least 2,500 steps on the ̶0;Beyond the Sea̶1; route.
Push the center button to bring up the main menu, then select the ̶0;PokeRadar.̶1; This will take you to a screen with four bunches of grass. Each bunch of grass has the possibility of hiding a Pokemon battle.
Use the left and right button to select the bunch of grass that displays an exclamation mark over it. This will activate a mini-game with the chance to battle a random Pokemon, including Horsea. You may need to activate the ̶0;PokeRadar̶1; more than once to find the Horsea.
Attack the Horsea Pokemon until it has only one bar of life left, then use the ̶0;Capture̶1; command. This will capture the Horsea, which you can then transfer back to your Pokemon game on the Nintendo DS.