I have looked everywhere and I have a swarm. Where do I need to go?
They appear in Violet City during a Swarm.
Fishing with the Super Rod is the only thing that will work. Old Rod & Good Rod will be ineffective.
Source: Bulbapedia/ Whiscash & Bulbapedia/ Violet City
How to change your username How to add a user avatar Why was my post hidden? The points system Question etiquette Flags vs Downvotes Anime FAQ
Type a Pokemon name, type, move or ability to see instant results.