Scizor @ Scizorite
Ability: Technician
Level: 50
EVs: 252 HP / 212 Atk / 44 Spe
Adamant Nature
- Bullet Punch
- U-turn
- Roost
- Superpower
Scissors is a great Pokemon to counter Mamo because Scissors is a pair of scissors, and Mamoswine is not a rock type, but it is an ice type which can be the same color as paper, so it must be paper, and by the rules of "Rock Paper Scissors" Scissors wins 100% of the time against paper. This makes Scissors the best counter.
Luckily for us we don't need to rely on Scissors in Rock Paper Scissors only. After cutting Kartanas (The top tier paper) for 20 years These Scissors Learned how to use Bullet Punch, which 2hko's any Mamoswine variant, unless it's physically defensive. Do not worry though, as Scissors has superpower, which KO's if a bullet punch is used first. 44 Speed lets the Scissors outspeed uninvested Mamoswine, making it even easier to KO.
Offensive Calcs:
212+ Atk Mega Scizor Superpower vs. 252 HP / 252+ Def Mamoswine: 136-160 (62.6 - 73.7%) -- guaranteed 2HKO
212+ Atk Technician Mega Scizor Bullet Punch vs. 252 HP / 252+ Def Mamoswine: 102-122 (47 - 56.2%) -- 78.9% chance to 2HKO
212+ Atk Technician Mega Scizor Bullet Punch vs. 4 HP / 0 Def Mamoswine: 150-176 (80.6 - 94.6%) -- guaranteed 2HKO
212+ Atk Mega Scizor Superpower vs. 4 HP / 0 Def Mamoswine: 196-232 (105.3 - 124.7%) -- guaranteed OHKO
Defensive Calcs:
252 Atk Mamoswine Earthquake vs. 252 HP / 0 Def Mega Scizor: 66-78 (37.2 - 44%) -- guaranteed 3HKO
4 Atk Mamoswine Earthquake vs. 252 HP / 0 Def Mega Scizor: 54-64 (30.5 - 36.1%) -- 44.3% chance to 3HKO