Mamoswine @ Choice Band / Life Orb / Expert Belt
Adamant - 252 Atk, 108 Speed, 148 HP
Oblivious / Snow Hide
~ Ice Shard
~ Earthquake
~ Stone Edge
~ Avalanche / Peck / Double-Hit / Stealth Rock
CB Mamoswine. The spread gives Speed enough to outspeed Adamant Max Speed TTar putting all leftovers on the great HP. Ice Shard is the main attack here and it's capable of dealing a lot of damage with STAB, enough to OHKO all things 4x weak to it(If my calculations are correct), Earthquake deals also a lot of damage overall, and Stone Edge is just a filler for things like Charizard whose are immune to EQ and take neutral damage for Ice Shard. Avalanche is a more powerful Ice move and can hit many things hard. Peck, for as laughable as it may be, OHKO's Heracross(If my calculations are correct). Double-Hit breaks Subs and Stealth Rock gives support.
Mamoswine @ Choice Scarf
Adamant - 252 Atk, 240 Speed, 16 HP
Jolly - 252 Atk, 204 Speed, 52 HP
Oblivious / Snow Hide
~ Ice Fang
~ Earthquake
~ Stone Edge
~ Double-Hit / Stealth Rock
The first spread allows Mamoswine to outspeed The base 125 with a +Speed nature, while the second allows it to outspeed CS Hera and all the ones that go for outspeeding It. Same move set, but with Ice Fang over Shard. Double-Hit breaks Subs and Stealth Rock gives support.
Mamoswine @ Salac Berry / Liechi Berry
Adamant - 252 Atk, 52 Speed, 172 HP, 32 Def (Liechi Berry)
Adamant - 228 Atk, 108 Speed, 172 HP (Liechi Berry)
Adamant - 252 Atk, 240 Speed, 16 HP (Salac Berry)
Jolly - 252 Atk, 204 Speed, 52 HP (Salac Berry)
Oblivious / Snow Hide
~ Ice Shard(Liechi Berry) / Ice Fang (Salac Berry)
~ Earthquake
~ Stone Edge
~ Substitute
The first 2 spreads take advatage of 101 Subs to activate the Liechi, obtaining the same effects as with a CB. The same goes to the spreads with Salac, but without 101 Subs.
Other Options: Curse, Rock Slide, Hail, Blizzard, Ice Beam
Curse can boost Attack and Defense, but Mamo isn't very good at pulling it off since it has low Special Defense, meaning if you set up on the wrong enemy(Fire Blast Garchomp), or if your enemy switches to a Special Attackers, you can see your effort in Set Up go away as you are forced to switch.
Rock Slide is always an option over Stone Edge due to better accuracy and Flinch cance.
Hail can be nice with Snow Cloak, but Mamo has better things to do than pray to luck.
Blizzard is the only other option that is worthwhile. It can hit many Physical tanks for a lot of damage(things like Gliscor and Donphan). Ice Beam is also viable.