Abra is like B-C. its got good offensive stats but its typing and defense fucks it over.
Dura and Cranidos are C to D. No way in hell are they B. Read the description of B.
Krabby might be a C. I haven't used it in forever.
Trapinch is a D mon. It has a very small niche. Its not totally shit, just mostly. All the other ones i agree with.