For in game only, doesn't matter, just go with whichever skill you like.

For competative battle, not recommended due to the number of weaknesses. Fire deals 4 times dmg since it's both grass and ice. Not only that, it receive 2 times dmg from poison, fight,  flying, bug , rock and steel moves. You need to run a good setup to make him viable, like Protect and Giga Drain due to its high S.Atk.  150 Giga Drain is strong.

Abomasnow can be good , weak when comes with a fire type. Because of him/her/it's ability , Snow Warning , It can summon a hail. If you wants to make a hail team.

Ice Shard , Wood Hammer , Protect are good skill on him/her/it's.