Well, it's between Audino and Alomomola. But I'd rather remove Audino because it's something like another "Chansey" duplicate. So far, here are the list of "reused" pokemons in Unova.
Klink, Klang, Klinklang = Magnemite, Magneton, Magnezone
Purrloin, Liepard = Glameow, Purugly
Patrat, Watchog =...