Using it on a stationary legendary is just silly. You have infinite tries there, just be patient. Also, you've got specialty balls that make things that much easier (Net Ball for Suicune, Dusk Ball for Mewtwo). I don't care as much about the other 2 dogs, so I used mine on Latias in my HG. Haven't gotten around to doing any of the birds yet besides Articuno, but that's just because I just happened to be there -- was incredibly easy (and lucky, I'm sure). Only took 3 Dusk Balls.