Boss - Avalanche Yeti

Like every other boss in this game, you should be using jump slashes with Zero's Glaive (maybe half Charges if you went the X route). 
 If the giant Snowflakes become too much of a problem, jump and use the sword spin to clear things out. You may clip Yeti with this attack but the iframe increase is not a lot with that attack. 
 If you have to tag in X or Axl, their Lightning attacks (from Manowar) are very effective.