A pre-evolution would be pointless and unneeded. If you want cuteness, there are already a lot of cute Pokémon out there and they will certainly create more.
I think that Game Freak should draw the line at Jynx and Banette as far as giving evolutions to two-stage Pokémon is concerned, and I wouldn't even necessarily suggest those two if their counterparts didn't have evolutions. But I should note that Jynx is also contrasted with the Tyrogue family due to her Psychic type and set gender. The two-stage Pokémon that really need evolutions are Parasect, Sudowoodo, Magcargo, Sunflora, Delcatty, Masquerain and Swoobat.
Something that I think would benefit from an evolution would be Mawile. Something that keeps line tied to the futakuchi-onna. Maybe she could become a Dark-type to fit with its deceiver nature.
I think it could be argued that Mightyena deserves an evolution more than any other two-stage Pokemon.
Poochyena is an early route Pokémon that was created to complement Zigzagoon, even though only the latter is seen as a Ratatta counterpart. They could give Mightyena an evolution, but that would unfair to the Ratatta, Sentret, Zigzagoon, Bidoof and Patrat families unless they all received evolutions, which is unlikely.
Who can use an evolution:
Pre-Evolution/Baby Pokemon for:
There's a lot of pokemon I'd like to see evolve. If only for the sake of seeing what would happen to their design.
I can't say there's a lot of pokemon I'd want to see baby forms of. I was never fond of the baby pokemon.
An IceFox who prefers fire types? That's... interesting.
I'm more partial to blues and greens as well~
There's so much they can do, but I do believe we will see something akin to Gen 4, with lots of Babies and 2nd stage evos.
-Emolga Pachirisu shared baby. While all the electro rodents share cheek dots, they have the same ones and same eye designs. Not to mention body shape is basically the same.
-Torkoal baby. Something small and cute, with a normal/fire typing ala Azurill. Also a Torkoal evo, with a steel second type.
-Druddigon evo. A one stage dragon doesn't feel right to me, and I could see em giving it an evo which would be even pointier. Maybe a more elongated body?
-Golurk evo. I know that its perfect in design, but something tells me the Golurk focus is a hint.
Those are basically all I can see them doing right now, but I could be wrong as well.
Scizor did was change Scyther's type and mix around some stats. Not really the conventional evolution. Especially for Heracross it wouldn't work unless they were to change its secondary type, which is something so definitive of Heracross I could never see it happening. And at this point Pinsir and Heracross are much more closely associated I couldn't see them giving the thing an evolution while they don't do it for Heracross. I think with those guys if anything we'll see a split evolution baby.
Lines that I'd like to see evolutions of (and are sort of realistic i guess):
Pokémon that I'd like to see prevolutions of:
Officially claimed Scraggy. GPXPlus profile.