How do you get the three legendary birds?

Moltres=Mt. Ember on 1 island
Articuno=Seafoam Islands
Zapdos=Abandoned Power Plant

For Zapdos you have to Surf to the Power Plant south of the pokemon center thats near the entrance to the Rock Tunnel. You will have to get to the exit of the power plant to find Zapdos.

For Moltres you need to gain access to Island one. Then travel north via Surf and enter the foothills by heading up the stairs. Then go to your right and you will come to a pair of boulders push the one nearest the wall away then go to the other pair and push the boulder nearest to the ledge away and continue to the stairs then walk to the right until you come across a set of unblocked stairs go up them and continue up the next set of stairs turn left and follow the path into a cave, go through this cave until you reach the exit and then go left until you come across a set of stairs follow these to the top. Next thyeir will be a small puzzle between you and moltres, 1. push the right boulder up, 2. push the left boulder left, 3. move up and push the left boulder left, 4.push the top boulder up and finally 5. push the last boulder all the way right. This done you will come face to face with Moltres.

For Articuno you have to get to the Seafoam Islands via the route south of Fuschia once there head into the first cave you see.now comes the tricky part getting through the maze. Go straight up the stairs and continue on until you go down another set of stairs push the boulder down the hole and follow it, do the same again at the next hole and the hole after this. Then when you have got to the next level Surf kicks in automatically surf north to the stairs but turn left and follow the path to another set of ladders climb up these go up the stairs and follow the path to a fork and go south first of all go to past the first set of boulders and push the boulder that's blocking the path all the way to the left and push the bottom one down in to the hole next go to the first set of boulders and push the furthest right one up then manouver the other one in to the hole by pushing it down once then left twice then down once again then left again. Then go in after it a surf up to meet Articuno ( I would advise buying an esacpe rope to get out).

Make sure you save before and after every battle with the three legendary birds and also buy lots of potions and ultra balls.

Happy to help

For Zapdos hes to the left of Celuran City at the Power Plant just Surf the water by the entrance to rock cave.

Moltres is on island 1 of the islands Bill takes you too after you defeat Blaine (8th badge)
Articuno is in the seaform cave just south of fushia he is a bit harder to find than the rest!
Good Luck

Zapdos-Power Plant

Articuno-seafom island

Moltres-One Island (Mt.Ember)

Moltres is in Mt. Ember Zapdos is in the Power Plant and aticuno is in the seaform islands