How do you get protector?

Route 228 for Diamond, for pearl/platinum I'm not sure

They are used to help protect things that are connected to the coax. It should be noted there is no real proof that there can be any protection from nearby lighting strikes or great voltage surges.

Go to profeser oak's house in enterna city after you get the pokeradar and go to pal park. his house is in enterna city, in the house across from the gym.he will give you a protector.

Give it to a Rhydon, and trade it. It should evolve into Rhyperior.

You can find it on Iron Island.