Please help me.

Now, i have finished all the story (from kanto to sinnoh). And i want to start catching legendary. To catch mew, i have read on forum that i must completed kanto dex. I have completed all dex in kanto, except legendary birds. But i cant find any legendary birds. I go to vitory road to see moltres, but he is not there. What can i do to get legendary birds seen data?

You should had seen data for Moltres in fight with him after earning all Kanto badges at the end of Victory Road Kanto (just before entering Indigo Plateau) and Zapdos lurks at Kanto Power Plant. For Articuno I didn't go for him, so I don't know where he is, but probably Seafoam Island.

I thinks so, but in fact i dont have any seen data for moltres although i have beat elite 4 kanto. And i go back to victory road, there are still no moltres there.

try talk to prof. oak's computer

try talk to prof. oak's computer

Thanks bro. You are our hero.