This is such a hard question since pretty much all of the Johto Pokemon are cute. :o
However, I would personally say Teddiursa, Mareep, Hoothoot, Sentret, Girafarig, Corsola, Togetic, Igglybuff, Cleffa, Smoochum, Magby, Marill, Misdreavus, Dunsparce, Yanma, Pichu, and Hoppip are all really...