I like Pokemon, as you probably already know, and although I've rather clearly designed Ruby to be a Buneary fusion, I lean a little more strongly towards making Choco a Vaporeon. I finally made the time to put his design to paper and while it's not what I'd call done, it's mostly there.

He's a smug little bastard, and his fin is a unique trait/defect/mutation that works as a quiff-analog. I'm thinking it would adversely affect its swimming (which is something I don't like much) but gives them better offense and access to some unique moves (like headbutt).