I Can't Catch Zapdos, Articuno, Or Moltres, What Do I Do?

When you get its hp as low as you can then either paralyze or put it to sleep. Wen it runs away start using quick balls I havent gone after them yet but I have caught cresselia & mesprit & every other legendary pokemon in sinnoh this should help you a lot

On pokemon blue I have found articuno and caught it ,I found zapdos but lost it and can't find it any1 know where it is its certainly not in the power station
also where is moltres

I'm having a hard time with them too. I say try to lower their HP down to red and use great balls and ultra balls until you catch them

Trap them with mean look.. Lower their hp and then chuck ultra and dusk balls at it. .

I'm going to assume you don't know how to stop them flying away?
Get a pokemon to use block or mean look.
Even if they do manage to get away they will have the same amount of damage on them if you did attack them and you CAN encounter them over and over and over =]
As long as you don't feint them and save afterwords they will forever be mocking you, flying around the sinnoh region. :P

Complete the pokemon league 250 times

I caught mespirit in an ultra ball so just keep useing ultra balls!

Buy a lot of ULTRA balls [99x] and keep on using them

You have to weaken them or put them to sleep and have patience.

First you weaken it to red hp. Then you put it to sleep and throw ultra balls at it. If it wakes up. Repeat these steps. If it doesn't work out for you, use timer balls

Use a Quick Ball when they have red HP. Try Ultra Balls if this fails.

If you have pokemon emerald, you could clone master balls, send them to your game and you will catch them easier. I did this and now I have moltres left.

You must save before you attack because you can only get one of the legendary birds I killed them but I only reset many times to catch them

I have pokemon diamond a platinum but I just got platinum yesterday and I'm going to get farther and my friend gots them on his marking map cuase he talked to prof.oak at eterna city the house next to the gym

Here's the secret.throw an ordinary pokeball at the legendary right away when you see the pokeball in the air then hold the b button and the forward part of the key pad once the pokemon is in the ball, let go of the b button but don't let go of that forward button