Dawn's Mamoswine (Japanese: ヒカリのマンムーHikari's Mammoo) was the fifth Pokémon captured by Dawn in the anime, and her sixth Pokémon in all.
In DP155, Mamoswine trained with Piplup as a partner but it did not go well. The same went for Pachirisu. Dawn's Cyndaquil was the one to work well the best with Mamoswine. During their practice battle against Zoey, Zoey's Kirlia used Psychic to control her Leafeon's Magical Leaf, defeating both Mamoswine and Cyndaquil.
Mamoswine, as a Swinub, was the first capture Dawn made since Buizel, exactly 50 episodes before. It is also her only capture in which she didn't battle the Pokémon twice, or even at all.
Mamoswine, as a Swinub, has some similarities with May's Munchlax: Mamoswine loves to eat mass quantities of Poffin; likewise, May's Munchlax enjoys mass quantities of Pokéblock (the Generation III counterpart of the Poffin).
Mamoswine is similar to Ash's Charizard in several aspects. Both Pokémon began disobeyed their respective trainers after evolution, only to begin following orders after each facing another Pokémon who severely injured them, they were the fifth capture of the trainers, and they evolved to their last stage 3 episodes after they were at their second stage.
Mamoswine is Dawn's First dual-type Pokémon, the second being her Togekiss.
Mamoswine is Dawn's second evolved Pokémon, the first being Ambipom. Both are final forms of a Generation II evolution family. Coincidentally, both need to know a specific move to evolve.
Mamoswine is the first Pokémon in the current saga to appear evolved in an opening prior to its actual evolution being shown.
Both of Mamoswine's evolutions happened during a battle with Team Rocket.
Mamoswine is similar to Ash's Gliscor in several ways. Both of them were their Trainer's fifth capture in Sinnoh and both are part of a Generation II evolution family. They also sat out of exactly three Contests/Gym battles before finally participating. Both are also part Ground-type.