Whimsicott and Lilligant are still weak to Ice. You also have Arcanine for Ice 'mons. Grass takes on Water, Rock and Ground effectively, but that type is still susceptible to other common types, like Ice and Fire.
Volcarona provides another Ice resist, though it shares weaknesses with Arcanine:
-Hidden Power (Ice/Ground)/Rage Powder
EVs: 4 HP/252 SAtk/252 Spe
Item: Focus Sash