Dunsparce, Chimecho, Mawile, Sableye, Murkrow.
Dunsparce: I like it the way it is, but any improvment is always welcome!
Chimecho: Poor bell... I like it, but it´s too weak, I see a soundproof evolution for it.
Mawile: The most creative steel Pokémon needs a creative evolution, I don´t know why it has an average big attack power if it learns a lot of Special attacks... A signature steel move for it is cool, like Metal bite.
Sableye: It´s Mawile´s counterpart. I know, not always what one get the other gets too (like Mantine and Skarmory), but Sableye would be nicer with a evolution, Keep it´s defenses and power up it´s attack and speed.
Murkrow: It´s the only Flying/Dark Pokémon, but also it´s the worst Dark Pokémon IMO... I like it, but I´d never use it in a battle...
Seriously, I think that neither of those in the list will evolve... maybe just one or two.