They look nice. BW Style it's ok, there are some things that you should detail better tho, like proper shading. I understand that BW Style doesn't involve much shading and uses more solid colors, but these lack defined light sources and anti-aliasing in some parts.
The grass starter it's nice, but the first and second evo needs more darker outlines for the cotton, as it looks quite plain in both sprites.
The fire starter's outlines are too dark when they're not needed, and too bright when it needs darker outlines. That, in comparison to your grass starters, which doesn't blend very well as a spriting "Style".
The evos are really cool. The first evo needs darker outlines and more shading. The second evo is perfect, I love it :)
I like mochi and mamechi's design, the first one looks like Hamtaro and the evo reminds me of Klonoa, or a Digimon in some way. These two doesn't have many issues, just Mochi's eyes, maybe they are too cute (?) They actually look too rough, add some anti-alias to them.
Rollbug and Thunderbug are just fine. They need more definition in the shapes that are used. I can see Thunderbug's left feet are almost the same, losing perspective.
Scooterbug and chiefbettle's only have problems with shading. The light source it's not clear.
I really like Torayuki, it seems as a common evolved pokémon though, not a legendary. It needs some brighter (just a little bit) outlines in some parts.
Overall, your work is fantastic and I really liked most of the sprites.