How can I catch the three legendary birds?

Articuno is found at Seafoam Islands
Zapdos is found at the Powerplant
Moltres is found at Mt Ember

A Good Team Would Be

Alakazam(Fire Punch, Psychic, Calm Mind, Ice Punch)
Heracross(MegaHorn, Swords Dance, Rock Slide, BrickBreak)
Scarmory(Drill Peck, Roar, Toxic, Spikes)
Sharpedo(Crunch, Surf, EarthQuake, Slash)
Blaziken(Blaze Kick, EarthQuake, Slash, Rock Slide)
Jolteon(Thunder Bolt, Hidden Power Ice, Sustitute, Thunder Wave)

To find the legendary birds some events will have to be fulfilled. To catch the nearest Legendary Pokemon will be Zapdos the bird of thunder will be at the Power Plant on Route 10. To do this you must first acquire the Fuchsia Gym Badge and HM3 which is Surf. On Route 10 near the Pokemon Center and the Rock Tunnal you will see a river stream this will led you to the abandon Power Plant. When you get inside the Power Plant there will be nothing but electric Pokemon and some Voltorb and Electrode that look like item pokemon balls on the ground keep traveling though the plant untail you reach Zapdos. Before battling Zapdos save your game first and make sure you have alot of ultra or great balls on you and some health items like Full Restore and Revive on you. When you battle Zapdos it will be at level 50 be sure to have some high level Pokemon on you levels 50-60 then happy catching but don't defeat it or you can't get it back if you did not save the game.
The next Legendary Pokemon is the bird of ice Articuno. You can find Articuno on the on the Seaform Islands off of the Fuchsia City and Cinnabar Island boarders on Route 19. There are two cave door entrances one from the side you take from Fuchsia City and the other side you take from Cinnabar Island you have to take the door on the Cinnabar Island side so start from Cinnabar Island and Surf to the cave door entrance. Once inside the cave you will have to go to a floor with holes in the floor and boulders as well you will need to use Strength a HM move to push push all the boulders in the holes of the floor don't push two or more boulders in the same hole once you did that drop in the hole and surf to Articuno on the little platform. Articuno will be at level 50 when you fight it like the other Legendary Pokemon Zapdos make sure to have Pokemon who's levels are 50 or higher. Make sure you save the game before battling Articuno. Make sure you have a lot of ultra or great balls on you and health items to like Full Restore and Revive to keep your Pokemon from fainting good luck with that.
The final Legendary Pokemon Moltres the bird of fire can be found once you beat the Cinnabar Island Gym. When you beat the Gym Leader Blaine and come out of the Gym Bill will come out and ask you if you want to come on a trip with him and do an erron for him you don't have to go right away if you don't want to but if you choose to do so you can get Moltres early but you can get it later after you beat the game and get 60 Pokemon in your Pokedex and get the National Dex. Moltres can be found on One Island in Mt. Ember you will need to push the boulder out of the way with the HM move Strength and you might need rocksmash another HM move. After you cleared the boulders then you will see a cave in the wall enter it then you will come to a room were you will find Moltres. As always you will need to save your game before fighting Moltres and be sure to have Pokemons who's levels are 50 or higher and have a abundance of ultra balls or great balls. When you fight Moltres it will be at level 50 if you defeat it without saving then there is no way to get it again so don't forget to save good luck.

For creating a good Pokemon Team be sure to have many different types of Pokemon in your team don't have a lot of the same. Another factor to include in building a good team is the moves you use have moves like amplifier moves like calm mind and sword dance those type of moves can make your Pokemon very powerful in there stats and make you unbeatable when used a certain number of times. Not only do you need to worry about what Pokemon to have but there move set as well the move you have could determine the outcome of the battle just say like if one of your Pokemon has a special attack move but it has a bad special attack stats then you should not use special attack moves because it won't do that much damage on that Pokemon then. Use moves that match the type your Pokemon is like dragon claw is a dragon move and Rayquaza is a dragon type Pokemon so that move would become more powerful since it is the same element as the Pokemon so you can take advantage of that feature as well. those are factors that could help you win a battle with a good team.

Thats easy when you get to it just save and if you kill it turn off you rgameboy and do it agian (use ultra balls)

Zapdos can be found at the Power Plant.
Articuno can be found at the Seafoam Island.
Moltres can be found at Mt. Ember.