I still have my LV 100 Pikachu which I traded over the Gens from Pokemon blue, where I originally caught it over 12 years ago. Its all about experience. =P
Gen I: I was able to get all of them due to having the Yellow version.
Gen II: Totodile
Gen III: Mudkip
Gen IV: Piplup
Gen V: Oshawott
What can I say? I love the water starter Pokemon for each generation. Although if I didn't have Yellow I would most likely have chosen Charmander instead.