I was recolecting on past Pokemon episodes and I remembered that proffesor ivy gave the g.u.s ball to ash and he gave it to kurt so he can open it( since no one else could open it) what ever happened to it after that?
It used to be that it contained Celebi. However the addition of Celebi in the 4th movie led to the writers to scrap that idea. So they just never mentioned it again.
