Get the scanner in the abandoned ship. Then, go to Slateport City. Go to the where the ferry is located and give the scanner to Mr. Stern. He will ask you to trade for his Deepseascale and the Deepsea Tooth. Choose either one of them, then give it to a Clamperl. This will raise its stats and allow it to evolve when traded. To get Gorebyss, give Clamperl the Deepseascale then trade it to a friend with a link cable. Then, have them trade it back to get Gorebyss. To get Huntail. give Clamperl the Deepseatooth and do the same thing.