The Pokemon that has the most creative name will have to be Squirtle. There's 4 descriptions that go into what creature it is.
Squirt = there are two meanings, as squirting water and a squirt as in tiny.
Squirrel
Turtle
Most complex in design is Eevee and it's evolutions. It took a lot of thinking just to make them all appear unique and different from one another. Sure Vaporeon and Glaceon can contradict each other because Vaporeon can learn Ice Beam and Blizzard and Glaceon can learn Water Pulse.