Dunno why Snover > Abomasnow. I guess it might look more tree-like with snow, but then again where I live snow is just about non-existent
Anyways, Snover is a typical Basic. 60 HP is standard, +10 Weakness to Fire is managable, no Resistence, but 2 Retreat Cost makes him hard to get out if you start with him. Curiosity is ok, as you can scout out your opponent's hand and determine whether or not you want to play that TGW in your hand. Snowball Fight does an ok 30 for 2 Energy, with a chance of 10 damage recoil.
Modified - 5/10 (Only option here if you want to use Abomasnow, which isn't terribly good itself)
Limited - 7/10 (I can see it being useful here with Abomasnow, splashable in a Water-oriented theme as well while offering different typing)
Unlimited - 1/10 (No business being here)
Christmas theme - 10/10 (Combine with Stantler, Jynx, and Delibird for maximum effect)