Guaranteed gym control?
So I have an idea of how to guarantee gym control during an ex raid. All you need is access to accounts on the two other teams with over 60 berries on each one.
Then you simply go into an account of the team controlling the gym and feed all the pokemon the maximum amount. (10 berries in 10 minutes) Then you can take the gym before they have a chance to golden berry anything.
This would more than likely require you to break the TOS and be a total dick move but in theory it works right? I hope to get gym control the right way and won't do this for the 2 extra balls
Answers
The one ex raid I was at the Valor team filled the gym 2 over hours before the event, then feed the Mons constantly. The first Blissey had over 148 berries feed and the others behind it were over 100 also don't know the final count. Our team was attacking for the fun of it and there were constant attacks on the gym from both rival teams. I would say your numbers are way low depending on the turn out and you better be ready to empty your bag or have plenty of others helping and only use golden raz's. There were about 100 players or so at the raid and we were all broken out by teams. Good Luck!