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 = Ratata, Raticate
Blitzle, Zebstrika = Ponyta, Rapidash
Pidove, Tranquill, Unfezant = Starly, Staravia, Staraptor = Pidgey, Pidgeotto, Pidgeot
Roggenrola, Boldore, Gigalith = Geodude, Graveler, Golem
Well, there's MORE, but you get my point right? The one that should replace Audino is Chansey, especially for all that exp stuff.