I'm going to say Piplup, because as much as I love Piplup itself, its evolved forms are my least favorite out of all the water starters.
aka Insanish Danish
Oshawott, but i like its evolution's
wow... piplup for the clear win (if you even want to call that a win)
Squirtle was the very first Pokemon I choose on the very first Pokemon Game I ever bought, Totodile is cute too and Feraligatr rocks, Piplup is sooooo cute and Empoleon is easily one of the best of Gen.4 deffensively speaking, and I actually have grown to like Oshawott a lot I don't get why all the hate. I have no words on Mudkip since I never choose him as my starter on R/S/E it was always treecko. :)
I seriously like all the Water starters (I always go with the Water starter for some reaon. It's just uncanny.), but if I really did have to choose which one is my least favorite, I'd probably choose Piplup. No reason given really, it's just the one I love a little bit less than the others.
Oooh I love all these water starters. My least favorite but still a favorite, is Squirtle.
Squirtle was the first ever starter I chose, but among all these water starters. He has the least use for me.
Kenta's Pokemon Party
Haha Piplup's the least favourite I knew it!
GIANT JIGGLY PUFF ROCKS
"Strong Pokémon. Weak Pokémon. That is only the selfish perception of people. Truly skilled Trainers should try to win with the Pokémon they love best". -Karen
"For every pokemon there is a purpose and a time when it can shine under the sun." -Blue1225