Fearow. Fearow needs a bit of love, and its rival -- Pidgoetto -- has an evolved form that puts it beyond Fearow's scope =/
I wouldn't mind a Marowak evolution, either. Dual-wielding bone clubs, perchance?
Staryu / Starmie line, named "Staruss".
Pre-evo or evo of Pinsir wouldn't be too bad.
Pre-evo of Lapras
Alternate evolution path of Dratini - Dragonair. I don't like going into Dragonite -- I'd prefer keeping the same slender, blue design, thanks.
Ariados. It's just plain weak, and bugs can always use an extra evo.
Dunsparce. It could use an evolution, really.
Sableye. It needs it pretty bad, and the concept is good enough to continue it.
Zangoose and Seviper. Would love to see both.
Buneary alternate male evolution
Glameow alternate evolution.