Poke Finder was a feature in S/M US/UM only where if you came to a spot on the map with a camera symbol, you can take pictures of wild Pokemon. You are only required to use the Poke Finder feature in story once during the Ghost type Island Trial. There are five different versions of the Poke Finder that will unlock more features. You unlock these other version by getting a certain amount of thumbs up.
Did you ever bother with Poke Finder and did you ever get Version 5? What did you think of this feature?
I never used it. It was an interesting mini game to put in there. I think it was put in there to be similar to Pokémon Snap. I appreciate the sentiment of them putting it in there, but ultimately never used it.
I've used it total of 2 times during my first playthrough. Once when the game shows you this feature and then during the Ghost Trial. It don't think I've even noticed single place I could use it and I don't remember there being really a reason to use it, aside from the upgrades. It could've been Snap minigame, but is pretty useless like it is in the game.
When it uses its special stick to strike up a beat, the sound waves produced carry revitalizing energy to the plants and flowers in the area.