Articuno is one of the few Legendary Pokemon that can be found within Pokemon FireRed, being one piece of the Kanto Legendary Bird Trio. In fact, Articuno will most likely be the first Legendary Pokemon you encounter within the game should you follow the story closely and don't backtrack. Articuno can be found at the bottom of Seafoam Island, which is located directly to the east of Cinnabar Island. Seafoam Island is a large icy cave that you must maneuver though by traversing the waters within, slowly going deeper and deeper within the cave by using the ladder system. Articuno awaits at the far bottom level of Seafoam Island.
Articuno will be found at Level 50, and it will know the moves Mist, Agility, Mind Reader, and Ice Beam. Since Ice Beam is Articuno's only attacking move, it's really the only thing you will need to worry about. Since Ice Type Moves aren't effective against Fire Type Pokemon, they are usually the way to go when facing this Legendary Bird. Articuno is also an Ice/Flying Type Pokemon, meaning its especially weak to Rock Type Attacks. Fire Type Attacks and Electric Type Attacks also hit Articuno extremely hard.
When looking to catch Articuno, always save directly before proceeding to battling the Legendary Bird. It's never fun when you accidentally defeat Articuno or if it defeats all of your Pokemon, but all of that is avoidable simply by saving directly before trying to catch it. Also, don't forget to purchase loads of Ultra Balls and Repels from the Poke Mart before going to catch Articuno. Repels will help you avoid facing Wild Pokemon leading up to Articuno in Seafoam Island, and Ultra Balls are the best possible Poke Balls you can use when trying to catch Articuno (since it's not worth using your one and only Master Ball on).
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