You can either:
A. Firstly, you'll have to get a Male Aurorus with Freeze Dry then breed it with a Female Lapras. Once its offspring comes out both Male and with the move Freeze Dry, you'll want to breed the Male Lapras with a Female Delibird, then its offspring will have to be Male with Freeze Dry. Now with your Male Delibird with Freeze Dry you'll have to finally breed it with a Female Swinub, Piloswine, or Mamoswine and it will come out with Freeze Dry. Finally get a Male Smeargle with Stealth Rocks to bred with your Female Swinub, then you've got your perfect Swinub.
B. To shorten the process just get a Smeargle and Aurorus in a double battle some where in-game and have it Sketch your Aurorus's Freeze Dry with Stealth Rocks and breed the two moves to your Swinub
Hope I've Helped :)