Question

How to get berries to spawn fast?

Comments

https://pokemondb.net/pokebase/331098/is-there-a-way-to-trigger-a-weather-change-in-the-wild-area The question about weather conditions was answered twenty minutes before you asked this. How did you not see this?
Also, if you want to ask two unrelated questions, please ask them separately.

Answer 1

There are a few ways to obtain berries in sw&sh. The first is to find a berry tree, and shake it until your satisfied with the berries that fall. Don't shake it too much or a Pokemon will attack you and steal some of the berries that dropped. Afterwards you won't be able to shake that tree for a while, but there are plenty of trees in the wild area so that shouldn't be a problem. Berries can also be found on the ground at various spots. One more way to get berries is to get some wishing pieces for some watts, and spam max raid battles. Try to hit 3 star raids as those are easier. Keep in mind that certain Pokemon will not drop berries. I hope this helped!

Comments

There is a way to get the maximum berries possible from each tree. Sometimes, the tree won't start to shake after you shake it once. Then you can keep going for a while. Normally, it will shake quite steadily after you shake it for the first time. Other times, it will shake quickly after you shake it. Once you get the tree shaking in the fast speed, you can normally shake it once more before a Pokemon will attack.