you cant catch it at Solaceon town but you can catch it on the west route of hearthome city
solaceon town
If you mean the Psyduck that sit in your way, you need to get the Secretpotion from Cynthia, then go to Solaceon Town (the Daycare one) and go north to the Café. The Psyduck will be next to the Café.
solaceon town has a daycare in Pokemon diamond and pearl
East of Hearthome city and south of solaceon town
Go to the tower in Solaceon City and catch a GHASTLY.
You get it from a man near Hearthome City on the way to Solaceon Town.
The Psyducks are right above Solaceon City.
You can get 2 eevees in Pokemon pearl by breeding the eevee you get from Bebe ( her house is next door to the Pokemon center in Hearthome city) with a ditto in the daycare center in Solaceon town.
it depends where it is i only know where it is in Pokemon pearl Pokemon diamond and Pokemon platinum the ruins are in solaceon town (sorry i only know where they are in those games sorry)
The Thunder Stone can be found in the Underground, Sunyshore City, and the Solaceon Ruins. The Thunder Stone is used to evolve some Pokemon like Pikachu.
If you're playing Diamond, Pearl, or Platinum, head north from Solaceon Town to the Psyduck blocking the road. If you are Playing HeartGold or SoulSilver, head to the top of the Lighthouse in Olivine City and give it to Jasmine.
Fantina will appear after you have visited these places in the following order: Solaceon Town, Pastoria City, and Celestic Town.