how to release bos george? I already captured the suicune and he still didn't release it .. I tried to do a quest, but the npc Scientis rey says something is missing

 

Hi there @Pisquillindo

Sorry for the inconvenience.

 

I would like to inform you that in order to start the quest, you will need to visit the place you fought the Guardian for the respective dogs at, in your case it will be Suicune, which is at the Secluded Lake. Once you've entered the map, you will receive a message stating that you should talk to Scientist Rey at Bell Tower. 
As a reference, please visit the Legendary Event Moves Quest

I hope that helped you. Let me know if it did.
Have a lovely day!

After catching one of the trios, talk to Scientist Rey. He'll ask you to collect missing Bell pieces scattered all around johto. You have to collect them by defeating some NPCs in order.
https://www.youtube.com/watch?v=KYdJZTT3uNM&t
Follow this guide to the find the locations of the NPCs. Hope this helps.