>>39706201The plush in OP's photo look like those from the Japanese 'Pokémon Fit' collection, AKA 'Sitting Cuties' in the USA. Some of these are surprisingly well made (some are wonky) and they have a good weight to them. For more obscure Pokémon this series is the only option for a well-made official figure/plush.
I don't personally know why someone would want hoards of them, but I'm planning to pick up my favorite one once Gen. II releases in the USA, and throwing it on a shelf corner or something.
I feel like one or two plush/figures in a room can be a tasteful accent, but when you collect lots and lots of these things it diminishes their collective value and gets kinda weird.