I dont know the terminology, but using single pixels over a brush size like 2x2, making putting them with other art difficult, a surprisingly large amount of art suffers from not meshing with other art
Ah yes, I agree. Having the pixels be actually pixels, not doubled or tripled, (if that's what you mean) is crucial. Also palette consistancy helps too :)
As for large pixel-art Bosses, I do plan on making more variety of them, I'm just not as good at animation yet so it takes a lot of time for me to make one. That's why I mostly stick to Tilesets.
But I do have a large Devil/Demon like creature currently in the pipeline :)