How does adding more Pokèmon to gyms work now?

Question

It used to be that you could train on your own gyms by attacking them, then once you got the points high enough from doing that, you could put a Pokèmon of your own in it. Obviously this mechanic has changed, but I can't figure out what it's been replaced with. The only thing I can figure out how to do is feed berries to any demotivated Pokèmon, but there's no indication that doing so opens up new slots. The little tutorial you can view when at a gym doesn't mention how to do it either.

How do I open up a slot to put my Pokèmon in a gym? (Or are the slots always open, and all the gyms I see just happen to be full?)

Answer 1

You can't open new slots with the new system. When your team captures a gym, it is automatically filled with 6 free spaces. Any player from your team can then add a Pokemon to it as long as there is space in the gym (and an identical Pokemon is not already present in this gym). It is not possible to get as many slots as it was possible with the previous gym system.