f***ing Cresselia...I was able to catch Diagla, Palkia, Giratina, Uxie, Azelf, Regigigas, & Heatran with Pokeballs (about 20-30 for each one...after a False Swipe & Thunderwave of course), Hell I even tossed a Great Ball at Mespririt and was able to get 'em, but Cresselia >_> I had to use a Master Ball on her...
EDIT: I forgot that I had to use an Icy Wind on Giratina...(I hate it's duel Ghost type)