Where to see wormadam in Pokemon diamond or pearl?

right below veilstone city there are a few trainers and one is a beauty its where the rails and the ruin maniac are who asks to have a race with unknown, this has nothing to do with it that's just where it is

Below Veilstone city, there is a handful of trainers, to get to the trainer with the Pokemon Wormadam. to get to the trainer go: down, then turn right, then down, left, down, right, and the trainer is a girl, a beauty. She has blonde hair