No, Leafeon an Glaceon DO NOT EXIST on GBA Pokemon games. No amount of cheating with AR/GS will get you these Pokemon on GBA.
If you want an Articuno on Pokemon Emerald you have to trade from Fire Red or Leaf Green. Or use a Game Shark.
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you can't. plain and simple
Mirage Island Game Shark CodeThere are no Gameshark Warp codes in Emerald to get to Mirage Island. There is a code but it will hardly work7572668C A25C844CUse this and maybe you can get there
I have no Idea but im sure you can find it on google just type pokemon emerald gameshark codes.