Special Attack: 44
Special Defense: 48
Avalugg has some great Defense and Attack stats, with a complimentary movepool such as Gyro Ball, Avalanche, Earthquake, Stone Edge, Crunch and Roar. It has a great ability, sturdy, which helps it live any super effective hit at full health. However Avalugg has one of the worst Special Defense stats ever, which means that any Special Attack will kill it.
+1 252+ SpA Choice Specs Sunkern Solar Beam vs. 252 HP / 0 SpD Avalugg: 393-463 (99.7 - 117.5%) -- 93.8% chance to OHKO
Special Attack: 110
Special Defense: 95
Vaniluxe has some decent defense stats, and a great Special Attack stat, but it's speed is lacking. With Ice Body as it's better ability it can function well in Hail. However it's movepool is quite bad. With only Blizzard, Flash Cannon, and Hyper Beam as it's most viable moves, it's quite limited in coverage. However it does also get Autotomize which can be used to fix it's bad speed and give it a sweeping shot.
Special Attack: 70
Special Defense: 80
This Pokemon has some well rounded, but below average, stats. His saving grace is his Hidden Ability Swift Swim which will boost his speed and give him a chance at using his Attack Stat. With a variety of moves such as Stone Edge, Shadow Claw, Bulldoze, Night Slash, Brick Break, Aqua Jet, and Superpower he can get a lot of coverage. He can also attempt a sweep using Sword Dance and Swift Swim.
Special Attack: 95
Special Defense: 135
This Pokemon has some really bad Defense and HP stats, but his Special Defense stat is quite good. He also has a good speed stat which can make him good for Speedy Support. With a nice supportive moveset like Reflect, Light Screen, Confuse Ray, Haze, Swagger, Toxic, and Hail, this Pokemon can effectively support a team if used right.
A Last Word:
Cryogonal is a decent Pokemon but outclassed by other Pokemon with better stats, and better HP.
Beartic is good in lower tiers where there's not much outspeeding him, but 50 base speed and poor Defenses just don't cut it.
Vanilluxe is a good Pokemon but sadly doesn't have the movepool to pull off anything more then a half-hearted sweep.
Avalugg has some great moves to compliment it's stats, but a poor special defense stat can get it killed pretty easily.
Of these four Ice types I'd say it really depends on what you need and who you intend to pair them with. Cryogonal could make a good pair with a frail Pokemon who wants some Screen protection. Beartic could be used well on a lower tier rain team. Avalugg can amke a nice slow attacker with Sturdy. Vanniluxe could pull off a last minute autotomize sweep. In all though I'd say the best ice type of these four is Avalugg due to his unique movepool and stats.