Moves
Earthquake is extremely strong, OHKOing offensive Jirachi, Shuca Berry Heatran, Tyranitar, and Metagross after Stealth Rock. It also generally 2HKOes most offensive Pokemon who don’t resist it such as offensive Swampert, Machamp, and Scizor. Ice Shard is strong enough to OHKO Dragonite and Flygon and 2HKO offensive Latias, Zapdos, and Breloom. Mamoswine is bulky enough to survive one boosted Extreme Speed from Dragonite and Breloom’s Mach Punch, letting it take on these Pokemon.
From here, Mamoswine’s options open up considerably. Ice Fang is Mamoswine’s best option to 2HKO defensive Latias, Zapdos after Stealth Rock, and frailer offensive Pokemon immune to Earthquake such as Gengar. However, Stone Edge is Mamoswine’s best move against Gyarados, who often tries to set up on it. Knock Off is another great choice, as it is Mamoswine’s best option against Skarmory, Bronzong, and defensive Rotom-A because it can’t hurt these Pokemon effectively. Removing their items not only helps Mamoswine wear them down, but also allows Magnezone to trap Skarmory if it has a Shed Shell.
Substitute helps Mamoswine take advantage of the free turns it generates, as opponents often switch to a faster Pokemon that can KO Mamoswine when it threatens a foe out. Substitute also helps against bulkier Pokemon such as defensive Rotom-A without Shadow Ball, as it can keep the Substitute and either threaten them out or PP stall it due to Ice Shard’s 48 PP. Another option is Superpower, as Superpower is Mamoswine’s best offensive option against Skarmory and Bronzong, but has redundant coverage with Earthquake. In general, Mamoswine uses Superpower and Stone Edge together on more offensive sets and Knock Off and Substitute with Leftovers.
Set Details
If Mamoswine isn’t using Substitute, it should always run maximum Attack and Speed EVs. With Substitute, Mamoswine can run 172 HP EVs to make 101 HP Substitutes to help against Clefable and Blissey. If it does this, one can run an EV spread of 172 HP / 144 Atk / 192 Spe with an Adamant nature, as this outspeeds Tyranitar and gives Mamoswine as much Attack as possible. However, this often isn’t necessary, as Mamoswine greatly threatens Clefable and Blissey anyway and is easily walled by other defensive Pokemon common alongside them. Mamoswine can run either an Adamant or a Jolly nature, as it both greatly appreciates the additional power on its Ice Shard or the extra Speed for neutral-natured Lucario, Heatran, defensive Latias, and Gyarados.
Mamoswine can use a couple of different items, as its sand immunity lets it hide its item effectively. With Substitute, Leftovers is an excellent option to make more Substitutes and potentially PP stall defensive Rotom-A. Mamoswine makes good use of Life Orb, as its immune to weather damage, is relatively frail anyway, and greatly appreciates the power boost especially on Ice Shard and Superpower. The residual damage unfortunately makes it easier for Pokemon like Dragonite and Breloom to pick it off. However, Never-Melt Ice is great offensive option, as it powers up Ice Shard and Ice Fang. Choice Band also can work, as Choice Band Earthquake is insanely strong, OHKOing physically defensive Jirachi, but all of Mamoswine’s attacks either have coverage issues should it lock itself into them.
Usage Tips
Mamoswine struggles to get in the game, as it doesn’t have any important resistances besides Electric. Try to get Mamoswine on predicted switches, U-turn, or with a sacrifice on something it heavily threatens or forces out, such as Dragonite, slower Heatran, Tyranitar, or Rotom-A locked into Thunderbolt. Use this opportunity to either set up a Substitute or hit something very hard. Note that Mamoswine’s coverage options such as Stone Edge and Superpower are often unexpected, letting it hit Gyarados and offensive Bronzong respectively quite hard.
Mamoswine typically gets in the game fairly late, once defensive options have either been eliminated or worn down enough for Mamoswine to break through. However, with Knock Off, try to hit Skarmory fairly early before potentially revealing Magnezone as once it is revealed, Skarmory will almost never willingly lose its Shed Shell otherwise.
Team Options
One of Mamoswine most common partners is Magnezone, as various Steel-types like Jirachi, Skarmory, Scizor, and Bronzong are debilitating for Mamoswine. Magnet Rise Magnezone can trap all of these Pokemon, opening the way for Mamoswine. Another great partner is Choice Specs Latias, as not only does Latias switch into many of Mamoswine’s weaknesses and batter Steel-types to potentially trap with Magnezone, it also appreciates Mamoswine harassing special walls like Clefable and alleviating it in dealing with Electric-types. As Mamoswine really struggles in dealing with Pokemon that resist Earthquake, it appreciates strong offensive partners that can break down Hippowdon, Shed Shell Skarmory, and physically defensive Rotom-A with Shadow Ball. Fighting-types like Breloom, Bulk Up Machamp, and Hariyama are fantastic partners, as they can bust up bulkier Pokemon to the point that if Mamoswine is behind a Substitute, it can clean up effectively with powerful Earthquake and Ice Shard. Mamoswine helps significantly in dealing with Dragon Dance Dragonite and typically can survive one hit from +1 Tyranitar, helping out Choice Scarf Pokemon such as Rotom-A who potentially struggle with these Pokemon.
Mamoswine is also a potent partner to teams heavily built around paralysis, as outspeeding foes and attacking behind a Substitute is very effective against more offensive teams. Jirachi, Azelf, Gyarados, and lead Breloom are highly effective partners, as they can also potentially wear down Skarmory and other Steel-types for Mamoswine. Gyarados is particularly effective, as it often draws in Choiced Electric-type moves and covers most of Mamoswine’s weaknesses, while Mamoswine can alleviate Thunder Wave’s Gyarados’s inability to threaten Steel-types like Metagross once it has paralyzed them. Metagross, Bronzong, and Heatran are also highly effective with Explosion, as that typically opens up a wall that Mamoswine struggles to deal with and Ice Shard helps them not have to deal with boosted Dragonite’s Outrage.