Articuno
Type Tier
Ice / Flying BL
Statistics
Stat
HP
90
 383
Atk
85
 268
Def
100
 298
Spc
125
 348
Spe
85
 268
Name Moveset

Standard Articuno

 ~ Blizzard
~ Agility
~ Double-Edge
~ Hyper Beam

Articuno has huge defenses and, basically, the strongest special attack in the game, which can severely dent practically everything. Blizzard does about 75% to Alakazam with a Critical Hit. It also does about 50% to Starmie with a Critical Hit; unfortunately, that isn't really enough to kill it on its own. So in order to get Articuno to work, you are either going to have to get rid of Starmie first, or freeze it, and based on experience, freezing isn't all that bad of an option. Considering Starmie needs to use Recover pretty much every other turn, you will get a fair amount of shots in, especially since Articuno has the defenses to switch in a number of times.

Chansey is another issue. Hyper Beam can help take her down, and Sky Attack OHKOes with a critical hit, though this is not highly recommended. Lapras can be a problem, but you actually can take it reasonably well with just Double-edge, since it has no real form of recovery. However, it will slow Articuno down.

So, basically, it counters a lot of difficult-to-counter standards (Exeggutor, Tauros and Snorlax, as well as Rhydon or Golem for the brave), but is also easily countered by other standards. Fortunately, with the right support, Articuno is a monster that will special sweep like very little else. It's also a great deal of fun to use.

Name Moveset

Staller

 ~ Blizzard
~ Ice Beam
~ Reflect
~ Rest

This set is more for Articuno to stall. Ice Beam is used mainly for freezing, while Blizzard gives you that extra power. Reflect and Rest keeps you alive with high defenses in both categories.

Other Options

Articuno can make good use of Mimic as its movepool is nothing special.

Opinion

Articuno is actually a surprisingly awesome Pokémon, considering all it can use are Ice moves. Its problem is that there just isn't much need for an Ice Pokemon in the metagame (although it's a pretty cool Exeggutor counter).

Counters

Starmie, Lapras, Chansey and Cloyster can all take Ice attacks and do a decent amount of damage back (save Cloyster who would most likely end up exploding on it if Articuno is worn down enough). Slowbro's initial Special isn't too great, but it can use Amnesia and Rest when it needs to. If you get Articuno paralyzed or you force it to Rest (assuming it has it), then a Rhydon or Golem could easily take Articuno down with a Rock Slide.