Catching the Legendary Bird Pokemon
After defeating the Kalos region's Elite 4, you will have a chance to encounter one of the three legendary birds from Pokemon Red and Blue throughout Kalos. Which bird will appear is based on the Pokemon you chose at the beginning of the game. The legendary bird should appear in your Coastal Kalos Pokedex afterward, allowing you to track its location. Walk (don't fly) to the bird's location to challenge it again; it should flee. Repeat a few more times, after which the Pokemon should retreat to Sea Spirit's Den. There you will at last be able to catch it.
