So your team is decent (meaning you used good Pokémon), but what it lacks is variety.
So to start out, this team will be crushed by Fire, Rock, or Steel types. Because of this, you need a Water type like Lapras or Cloyster.
Lapras @ Assault Vest
Ability: Water Absorb
EVs: 252 SAtk / 252 HP / 4 SDef
Obviously this is just a set I like, and you can change it around if you want.
Cloyster @ White Herb
Ability: Skill Link
EVs: 252 Spd / 252 Atk / 4 HP
- Shell Smash
- Icicle Spear
- Rock Blast
- Razor Shell
Cloyster is an amazing sweeper, requiring only 1 turn to set up a Shell Smash before becoming practically unstoppable.
So that solves the Fire and Steel problems, but what about Rock types? Glad you asked. Use Mamoswine.
Mamoswine @ Choice Band
EVs: 252 HP / 252 Atk / 4 Spd
Ability: Thick Fat/Snow Cloak
- Ice Shard
- Stone Edge
- Icicle Crash
So switch out what you want, but you definitely will want Water and Ground types on your team
Now I guess I'll rate the individual members.
This might be one of the Pokémon you want to get rid of. Honestly, its only use is Snow Warning, and you can use Hail just as easily.
Froslass would probably be a better lead than Abomasnow, being able to set up Hail and Spikes before fainting. I'm assuming Blizzard is for Taunts.
Nice special sweeper. If you want, you can make it fast by giving it a Timid nature, Speed EVs and a Choice Scarf.
Really, Cryogonal's only use is to spin out Stealth Rocks. Keep it if you want, though, since it's kind of vital to be able to do that. If I were you, I'd replace it with a Pokémon that I suggested and put defog on Articuno (thank heaven for Roost).
If you can (i.e. if this is Showdown and you can choose the Natures), give it a Timid nature and train it this way: 252 HP / 252 Spd / 4 Def. This makes it fast, yet tanky. And switch Substitute for Defog.
Rotom - F
Great special wall. Since it's not trained physically, give it Will-O-Wisp instead of either Substitute or Blizzard.
So overall, not bad, especially for a noob! :P
If you have any questions, please ask them.
Hope I helped!