Castform (from all 70 to all 90?
Sableye perhaps? Would be hax though since it has no weaknesses.
I think Marowak could use an evolution.
Also I think these pokemons deserves a junior form (baby form). An evolution would be cool too:
That's all I can think of atm.
P.S. I didn't take into account any background stories of these pokemons that may have been revealed in the anime (which I don't follow).