In the Japanese game, there was a special feature so you could Catch celebi. But, they got rid of the feature in the American version. That weird shrine thing, in that one forrest, you put the ball in that, and Celebi appears or something like that~
But it wasn't in the American Version. *naturally* the anime sorta' followed a similar pattern. Some episode was probably not shown in america, I dunno.
But I'm pretty sure the ball is empty, and It wouldn't open until it's *in* the shrine. Maybe Celebi's in it, and when it's in the shrine, Celebi releases, and you have to catch it. I don't know. Any Japanese PC members out there willing to answer?