Articuno

Articuno’s Blizzard is the strongest attack in RBY that is not Explosion or Hyper Beam. It can even outdamage Mewtwo’s mighty Psychic against neutral targets if both are unboosted. Articuno specializes in tearing huge holes in opposing teams, achieving things like 3HKOs on Mew and Snorlax, 2HKOs on Tauros, Exeggutor, and Zapdos, and clean OHKOs on Rhydon and Golem. Blizzard is very easy to spam, as even resistant Pokemon usually take noticeable damage. The move also comes with a nice chance to freeze and disable a foe for the rest of the game. Articuno also is decently bulky and can take a few strong attacks. For example, Tauros's Body Slam usually takes less than a quarter of its health, assuming it does not get a critical hit.

However, Articuno's movepool is abysmal, with almost exclusively Ice- and Normal-type moves to choose from. The latter come off of its mediocre Attack stat, leaving it unable to deal with certain bulky Pokemon like Cloyster and Starmie. Articuno is also rather slow, requiring paralysis support or an Agility in order to function effectively against faster Pokemon. Articuno's low Speed also prevents it from functioning as a good lead, as it is outsped by common leads like Gengar, Jynx, and Starmie. These weaknesses can make Articuno hard to fit on teams at times. Still, Articuno's devastating Blizzard will reward you handsomely for the compensation it needs.