Not really. Icicle Crash 3HKOs Skarmory so the only way of countering would be using Whirlwind. If Skarmory flinches, Mamoswine wins. But then again, Icicle Crash has a 10% chance of missing.
252+ Atk Life Orb Mamoswine Icicle Crash vs. 224 HP / 252 Def Skarmory: 125-148 (38.2 - 45.2%) -- guaranteed 3HKO
Anyway,
Xatu (M) @ Rocky Helmet
Trait: Magic Bounce
EVs: 252 HP / 252 Def / 4 SAtk
Bold Nature (+Def, -Atk)
- Heat Wave
- Roost
- Reflect
- Psychic
4 SpA Xatu Heat Wave vs. 224 HP / 32 SpD Skarmory: 170-200 (51.9 - 61.1%) -- guaranteed 2HKO
0 Atk Skarmory Brave Bird vs. 252 HP / 252+ Def Xatu: 97-115 (29 - 34.4%) -- 4.8% chance to 3HKO