Pokemon Sliver How To Catch Phantom In Pokemon Leaf Green, Is It Possilbe To Catch A Legendary Bird Such As Zapdos Or Moltres With A Ultra Ball?

In pokemon leaf green, is it possilbe to catch a legendary bird such as zapdos or moltres with a ultra ball? - pokemon sliver how to catch phantom

Is I've tried so many, but it never works, the birds have almost no HP have a red stripe, is that possible? has done? How U?