SM Monotype is one of the few metagames that I am comfortable with, so I would love to give your team my honest and detailed review.
Firstly, I will talk about your individual movesets. Then, I will talk about your team composition. Feel free to take all or none of my changes. It's up to you!
In my discussion, I will mention the match-ups that Ice would have the most difficulty with, primarily the Fire-type and Steel-type match-ups.
Ninetales-Alola: Your set here is great. Nothing much to change. You can try using Encore instead of Blizzard to help your match-up against walls and bulkier teams, but that's a small concern.
Rotom-Frost: Your Rotom-Frost moveset is fine as well. You do not need both Will-O-Wisp and Thunder Wave. I would drop Thunder Wave, and get Pain Split with it to improve recovery.
Glaceon: The moveset is fine, but you may find it difficult to hit any Fire-types with Water Pulse. I would recommend using Hidden Power Ground because that might be able to catch Fire-types, like Heatran, and steel-types, like Magnezone, off-guard.
Mamoswine: This moveset is also fine, but you should have Stealth Rocks on it instead of Rock Slide. This helps with the Fire-type match up massively.
Sandslash-Alola: Good set! I would use Earthquake instead of Counter. Your current set would also be completely fodder to Magnezone. Invest fully in Attack and Speed, so you can hit a higher speed tier when your Sandslash is under Hail.
Crabominable: This moveset is also fine, but I think Ice Hammer is better than Ice Punch.
Overall Team Composition Analysis
Currently, I do not see a way for your team to reliably deal with Steel-types and Fire-types. Threats like bullet punch Mega Scizor and scarf Magnezone can easily run down your team. Fire-types, like Volcarona and Mega Charizard X, are also big threats to your team.
Defensive walls, especially Sableye-Mega, can also prove difficult for your team to break through, due to a lack of hard-hitting wallbreakers.
Team Composition Changes
Here are some changes that I would suggest to make your match-up against the Fire-type and Steel-type teams stronger.
Firstly, I would take a look at your team and think about what Pokemon do not offer much utility. For instance, what does Glaceon offer that Rotom-Frost does not? Both are special-attacking Ice-types that use Blizzard. However, Rotom-Frost has the added benefit of being able to spread status conditions and pivot between Pokemon using Volt Switch. What does Crabominable offer that Sandslash-Alola or Mamoswine does not? Sandslash-Alola is faster than Crabominable under Hail, and Mamoswine with Life Orb hits harder than Crabominable.
I would recommend replacing Glaceon with Lapras, and Crabominable with Kyurem-Black or Weavile. The reason being is that Lapras can also be a strong special attacker, but it also offers a neutral resistance to fire, which your team sorely needs.
Kyurem-Black and Weavile are simply stronger threats than Crabominable. Kyurem-Black has impressive wall-breaking abilities with its mold breaker-like ability, and Weavile also helps greatly with the Psychic-dominated generation 7 monotype metagame.
Here are some sets I have received from Smogon:
Lapras @ Choice Specs
Ability: Water Absorb
EVs: 80 HP / 252 SpA / 176 Spe
- Hydro Pump
- Hidden Power Fire
Kyurem-Black @ Life Orb
EVs: 4 Atk / 252 SpA / 252 Spe
- Fusion Bolt
- Ice Beam
- Earth Power
Weavile @ Life Orb
EVs: 252 Atk / 4 SpD / 252 Spe
- Knock Off
- Icicle Crash
- Ice Shard
That's it! If you would like to keep your Pokemon, please consider the movesets that I recommended. If you would like to change up your team, the team composition is a great place to start. Let me know if you have any comments or questions.