Can someone tell me how to catch Zapdos without a Master ball?

1. Get as may balls as you can.
2. Get a Pokemon with thunder wave.
3. Save before talking to Zapdos.
4. Paralize Zapdos and get him in red health.
5. Throw the balls.
6. If you run out use soft reset and repeat until you catch it. (You may need to get more balls)

The best way to capture any Legendary Pokemon is to use a Pokemon that has False Swipe and raise it high enough to hit it all the way down to 1 HP. Then put it to sleep, paralyze, or even freeze it.

How to catch Legendarys easier

Get about 25 (if you dont have much luck at catching them) ultra balls, and a Pokemon who knows a move which puts them to sleep (sleep powder,sing and more). 1st thing put it to sleep and hack away. Every time he wakes put him to sleep again. When it gets to low health use a non-effective move to get him to a sliver of health. Now when he is asleep start throwing balls. Now it might be my game or just me but when it goes in the ball hold A and B down, then if the ball moves right hold Right down, same as left. After 3 rolls hold up. Even if this does not work it takes about balls when he is at low health and asleep cause 1st the ball opens straight away,2nd rolls once,3rd rolls twice, 4th rolls three time, 5th Congrats you should have caught it.

I just caught lvl 50 Zapdos by attacking with lvl 40 Charizard and putting it to sleep with a lvl 40 Venasaur.

I took a lvl 31 Onix in with full hp used dragon breath until zapdos was paralized and proceeded to get its hp as low as possible, was easy because it couldnt hurt onix very much and was also paralized. With onix being so low i could contol my damage without killing it and used about 4 ultra balls to catch zapdos.