More or less the only 'custom brush' I use is an eraser that I modified to have the same properties as the watercolor brush, but you can do that right in the interface: just look at the settings for the default watercolor brush and then create a new eraser that copies those settings. Of course, at the sizes most people will be seeing your artwork it probably won't be noticeable without close scrutiny, so if you prefer the smoother lines from the regular pen or the program you choose doesn't have a similar brush available, that's fine, too! If you zoom in close to a piece of actual Sugimori art (see here for an example), you'll see that the lines aren't perfectly smooth the mapping pen gives something reasonably similar for basically no extra effort. I do like using the 'mapping pen' brush for lineart these days, as it gives the lines a slightly 'rougher' feel.

You can easily get away with the pen brush for inking lineart and either the watercolor brush or the pen + a soft eraser for shading/highlights. I use MediBang as well (albeit the Android version moreso than the PC version), and all the brushes I use are there by default. Definitely looking forward to boopsie's evolutions-it's supposed to be eevee-like, right? Lots of potential in the base you've got there are plenty of brushes you can experiment with in any program if you want to! Thing is, I personally find that I don't really need any fancy brushes for Sugi-style art if that's what you're after in particular. I wish I had the patience for both this and pixel art, haha. In the meantime, eh, close Plant Zone, I really like what you've got there! I've been admiring the sprites you posted in the feedback thread, and the Sugi-style art is just as nice. Maybe as I continue adding new stuff/revamping all the old, ugly, chalky-looking stuff (why is that hideous mega arcanine still on my website aaaaaaaa) I'll eventually settle on something that looks good across the board. I don't think I've really nailed down a consistent personal version of a Sugi-esque style yet, heh-a lot of even my newer artwork tends to fluctuate between looking more like one generation or another.

And then there's the little guy in my avatar and its evolution, the ice/poison runnino and rhinovire.

Lineart brush paint tool sai