Getting the upper hand with your electric type against some tough water pocket monsters in Pokémon Brilliant Diamond and Brilliant Pearl is the key to victory, and the MT43 Volt Switch can help you triumph under these circumstances. Here's where to find it.
First, go to the lovely Hearthome City which is located in the center of the Sinnoh map. It is to the right of Mount Coronet and southwest of Solaceon Town. This "friendly city", as the game says, is home to Friendship Square, where you will find the MT43 Volt Switch. From the Pokémon Center, go northwest until you find the landmark west gate.
This is where you will see a porter blocking your way to the Plaza unless you have a cute Pokémon with you. We used our Torterra. Go inside and go south of the large fountain. To the right of a man with his Pikachu, you'll see the Volt MT43 switch slightly obscured by trees. Collect it to capture the electrical attack.
You can also find the Attraction move in Friendship Square. Go northeast from your location and you will find it.
Volt Switch has a decent power of 70 and a very good 100 accuracy. It also has a higher PP than Thunderbolt as the Volt Switch has five other uses. While it is very useful for the early stages of the game, it has a frustrating caveat. The Pokémon using the Volt Switch must be exchanged with another party member after using it.