All of the answers are names of Ice-type pokemon, either legendary or in their highest (or only) evolutionary form.
Across
A wily Dark pokemon that hunts in packs. It slices with its wicked claws.
A legendary Dragon that fell to Earth in a meteorite, according to Unova legends.
A large blue pokemon known for ferrying people across the waters of Kanto.
A walrus-like pokemon that hails from Hoenn. It is blue and white.
A snowflake-like pokemon that attacks by whipping its icy chains.
A penguin-like pokemon that stores food in its tail.
A large brown pokemon with giant tusks. In the anime, Dawn has one.
Down
A large Grass type from Sinnoh, where it is known as the Abominable Snowman.
A ghostly pokemon that is always female. It evolved using a Dawn Stone.
A strange pokemon that resembles a double-scoop ice cream cone.
A legendary bird of Kanto that causes snow to fall wherever it flies.
A Psychic type that puts opponents to sleep with a kiss.
A round pokemon with black spikes for horns. It can float and manipulate ice.
Eevee evolves into this pokemon when you level it up near an ice-covered rock.
A legendary golem of Hoenn. It cannot melt, even if it is submerged in hot magma.
This bivalve with a spiky shell was evolved using a Water Stone.
A large ursine pokemon that makes fangs and claws out of ice by freezing air.
A pure white pokemon with a flowing tail. It bashes icebergs apart with its horn.