How do you get Swinub in Pokemon Diamond?

Swinub are swarm Pokemon, so you have to wait for a swarm with swinub to occur after you have the national pokedex, which you get for seeing all the Pokemon in the Sinnoh pokedex except manaphy. Swinub usually are near Snowpoint City, on the route to the left. Talk to Dawn's/Lucas' little sister in the second house on the bottom of Sandgem Town. Also, the t.v.s may talk about a swarm occurring. Also, to evolve it into mamoswine, make it evolve into piloswine, and go to the move remember guy in Pastoria City at the house to the far left. you need a heart scale to teach it ancient power. Now just level it up once and you have a mamoswine.