I think Farfetch'd, Raticate, Rapidash, Sandslash, and Jynx should get evolutions.
Farfetch'd and Raticate have horrible stats and deserve an evolution. Rapidash may have great Attack and Speed stats, but it just needs an evolution. Sandslash may have Sand Rush, good Attack and Defense, and a good movepool, but I don't think that's enough. And if Electabuzz and Magmar got an evolution in Generation IV, why didn't Jynx get one?
Jynx ounterpart, if I am not mistaken is Mr.Mime, wherein both of them gained a pre-evo, although Mr. Mime's came three generations later after Smoochum.
On topic, I guess most of the water types should gain an evo, like Golduck and Seaking. Their design is good already, but their stats just do not match with the final evo stat. Also, I want Farfetch'd to gain an evolution AND a pre-evo. To fix his very unusable stats, he needs to grow more, so that people would notice him more. And just for cuteness, a pre-evo of him.
Lapras needs a pre-evo, and so does Tauros (which could be a branched evolution to Miltank. I have seen a few fakemons, and they were good)
EEVEE NEEDS OTHER FORMS. There are still several possible forms for Eevee like rock, Ground, or Steel. He could even be a flying type, depending on the situation.
On the other topic:
I think Lickylicky and Tangrowth were... Uhmm... Unnecessary evolutions. Yes, their stats went up, but did it significantly? They were also just enlarged versions of their pre-evo's. One might say that Magnezone looks like Magneton also, but hey. At least, Magnezone can do way more than Magneton.
Electivire and Magmortar were just plain awesome. And so is Porygon 2/Z.