I like the drawing of, um, the Pokemon in the grass hat. You're clearly not bad at this, and if I compare what you've just posted to what's at the top, I can see a difference as far as improvements. I feel like you can really only go up from here.
Not let's get into detail. The One Who Wears The Hat, you know it'd take less time for me to just look the name up, has really clean lineart, and the only spot that it's a bit off kilter is on its left arm (we're looking to the right). I sort of feel like you know this already. The shading style does feel like something Sugimorit would do, I think you acheived that. However, Sugimori doesn't seem to use black outlines. At least as far as I can recall. The only thing I'd say that isn't pointing out the obvious is that I would've used a hard brush to place the white highlights on the eyes. As of now, it's just a bit fuzzy.
Now, is Froakie wearing a jetpack or something? :P Looks kind of funny (in a haha way) thinking about it like that. I'd've made the mouth more clear overall, but otherwise, to learn a painterly style requires a tutorial, an instructor, or just really really good intuition. It's really really hard to explain how to do right off, especially in text, and I don't have all the firmest graspings of it myself, despite knowing how to do it
technically (I'm super stressing "technically", because I can, but almost always choose not to, so I'm much less skilled at it than people who do it as their preferred illustration choice). It's going to require a willingness to experiment at first, sort of get a feel for different brushes, and the effect that they have, and knowing what textures look good and where and why. It's also going to take a lot of time to go in and really start digging away at the details depending on the level of realism you want (even a more abstract painting still requires going over it with details).
Also, look into color theory and color harmony if and when you get a chance. You may not understand it at its fullest right away, but once you do, you'll love it. Check out this gamut mask:
https://www.livepaintinglessons.com/gamutmask.php
Usually when people do a painterly style, they often use only a certain range of colors, and then those that add an effect of brilliance (brightness) to a piece, or will set a mood.
That's the best I can do to give you an idea. There's also many tutorials out there, but everybody teaches a different style, and at that, they're teaching you
their methods. Because there is no one way to do things, it gets messy, so I'd try to find someone who matches your level of understanding first. You can always work your way up from there once you have a foundation of how everything works.