Ok, this is a step by step way to get them:
1. Go to Pal Park in the southern area of Sandgem Town if you didn't already.
2. You'll find Prof. Oak there and he'll say you can find many pokemon here for your pokedex. He'll then leave and say he's going to stay in Eternal City.
3. You should then go there. You'll find him in the southwestern-most house.
4. Go inside and talk to him. He'll say that the three legendary birds have been spotted over Sinnoh.
5. These Pokemon will do the same thing as mesprit and Cresselia; run away.
6. A good strategy is get a Lv.60 Mismagius with shadow ball and mean look and then start using max repels once you're in their area.
Hope this helped!
1. Go to Pal Park in the southern area of Sandgem Town if you didn't already.
2. You'll find Prof. Oak there and he'll say you can find many pokemon here for your pokedex. He'll then leave and say he's going to stay in Eternal City.
3. You should then go there. You'll find him in the southwestern-most house.
4. Go inside and talk to him. He'll say that the three legendary birds have been spotted over Sinnoh.
5. These Pokemon will do the same thing as mesprit and Cresselia; run away.
6. A good strategy is get a Lv.60 Mismagius with shadow ball and mean look and then start using max repels once you're in their area.
Hope this helped!