How do you catch the wild dogs in Pokemon heart gold?

Answer 1

For Suicune: You'll first see it in the north of Cianwood City. After you encounter it there, you can find it outside the entrance of Mt. Mortar in Route 42. After that it will leave Johto and head to Kanto where you'll need to go to Vermillion City. Next you will see it in Route 14, and it'll run away for the last time. You can find it outside Bill's House in Route 25. This is where you battle Suicune.

For Entei and Raikou, you just need to be on the same route as them (check the map on the pokegear for this), and if their face icon is under yours then you know you're on the same route as them, so you can catch them. (Just be sure you're in the Johto region).