Articuno, the Freeze Pokémon, is listed as number 144 in the National and Kanto Pokédexes and number 235 in the Johto dex (240 in the HG/SS Johto dex). Its Japanese name is Furiizaa (フリーザー). It is 5'07" long (1.7m) and weighs 122.1 lbs (55.4 kg). Like most legendary Pokémon, it cannot breed or evolve. Its base stats are HP 90, Attack 85 Defense 100, Special Attack 95, Special Defense 125, and Speed 85, and its Ability is Pressure. A list of the moves it learns can be found at Veekun.
Articuno's Pokédex information is as follows:
Red/Blue/LeafGreen: A legendary bird Pokémon said to appear to doomed people who are lost in icy mountains.
Yellow: A legendary bird Pokémon. It freezes water that is contained in winter air and makes it snow.
Gold/HeartGold: The magnificent seemingly translucent wings of this legendary bird Pokemon are said to be made of ice.
Silver/SoulSilver: One of the legendary bird Pokémon, it chills moisture in the atmosphere to create snow while flying.
Crystal: Legendary bird Pokémon. As it flies through the sky, it cools the air, causing snow to fall.
Ruby/Sapphire/Emerald: Articuno is a legendary bird Pokémon that can control ice. The flapping of its wings chills the air. As a result, it is said that when this Pokémon flies, snow will fall.
FireRed: One of the legendary bird Pokémon. With its long tail trailing behind, its flying form is magnificent.
Diamond/Pearl/Platinum: A legendary bird Pokémon. It can create blizzards by freezing moisture in the air.
You can view a gallery of Articuno sprites here.