If you don't see it, you probably missed it back in Johto somewhere.
You should of saw it in the Burned Tower, north of Cianwood City, and the berry trees outside of Mt. Mortar. This is for Pokemon Soulsilver and Heartgold.
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After you find suicune throughout johoto then beat the elite 4 you will get a ticket to kanto.When you arrive in kanto you will have to locate suicune in kanto aswell (where suicune is i still dont know)but i do know that after it is tired from running you will have to go to route 25 (out side bills house north of cerulean city )
If you can't find Suicune, then that either means you never visited the Burnt Tower in Ecruteak City or you haven't arrive at the Kanto region yet. To find Suicune, you'll need to first go to Ecruteak City and go inside the Burnt Tower. Go to the basement of the tower and you'll see Suicune, Entei, and Raikou. As soon as you see them, though, they will all run off, except for Suicune who will look at you before running away. After that, you'll have to chase Suicune at various places in the game before finally seeing it outside of Bill's House on Route 25, after Misty returned to her gym.
if you go to the burned tower in eckreteak city raikou suicune and entei will be there if you go down the ladder in the back they will all flee you dont get to battle them after that raikou and entei will roam around johto and you can see their locations on the pokegear map you dont get to fight suicune until later in the game
It's not really in Fushia, but its not too far away. Just keep walking east from Fushia until you meet the shoreline. Here you will see Suicune walking on the water. PS. This is the last place you need to find Suicune before you can catch it.
Go to vermilion city and head south to the port talk to the sailor he will see your tri pass and allow you back to islands 1-3