Cloud Nine Lickitung. In-game he only has standard moves of Lick, Supersonic, and Defense Curl, so no need to back up anything except the ability.
Edit: More coming since that was my copy of Black and I still have my copy of White to go...
Edit 2: Here we are!
Ponyta, Exeggcute, Farfetch'd, Stantler, NidoranF, and Oddish. That was kind of a tough choice since I really love the concept of Harvest and want to try it, but it was too hard to pass up on having both Nidoqueen and Nidoking. I also saw a Bidoof, but didn't bother completing the minigame that would have befriended it:
NidoranF has the Hustle ability and knows Scratch, Tail Whip, Double Kick, and a new move in Sucker Punch, previously exclusive to the male side of the Nidoran line:
- see Hustle abliity
- see Sucker Punch