I explain my problem. I'm doing the Celebi quest. I'm helping myself with this page (https://pokemonrevolution.net/forum/viewtopic.php?f=119&t=79853#at_celebi).
I have done all of the 3 first parts of the quest without problem (i just don't have 750+ hours playing, only 523).
So i fought the 3 legendary dogs, ho-oh and lugia but the NPC Scientist Alexander does'nt want to give me the GS ball back.
I already saw celebi in Ilex Forest near the shrine and i don't know what to do after that? Is it bugged or have i done something wrong?