You can buy a link cable from mudkip upstairs in the house. I think under the Evolution section. But does this work? Not sure, as certain pokemon that normally need to trade to evolve (Like kadabra) seem to not be effected by it
Use a prism scale on feebas like it's an Evolution stone. If that doesn't work, use it while it's already holding a linking cable. Idk if that last part is necessary, mine just happened to be holding one when I used the prism scale
