How do you catch a exeggcute heart gold?

You can catch them at route 29, route 30, route 31, route 32, route 34, route 35, route 36, route 37, route 38, route 39, route 43, route 47, route 48, Cherrygrove City, Ecruteak City, Lake of Rage, National Park, New Bark Town, Safari Zone Gate, Violet City, route 26, and Route 27. I know that that is a lot of places.