mr. mmj got Feebas; I'd like to add that Feebas, apart from being the combination of feeble and bass, like mmj said, is also meant to sound similar to "sea bass".
Milotic will require further analysis, I'll edit this when I come across a conclusion.
Finally, a theory. I was almost going to check this one out somewhere, but I couldn't: first, I have my pride (a big one, for that matter) and second, Milotic is one of my favourite Pokemon, I
had to figure it out on my own.
My theory is: Milotic has something to do with "melodic", probably. "Milot" is the hard part. There's no such thing as "milot", not that I know of... But there
is a thing called Milo. Venus de Milo, the statue of Aphrodite/Venus that represents
beauty. Milotic is said to be the most beautiful of all Pokemon, so I guess it's kinda fitting...
So I guess that could be it... a mix of "melodic" and "Milo"... loooong shot
besides, I'm not sure the creators of these names would use an artistic/historical reference in Pokemon (a children's anime), but oh well.
Milotic = Milo + melodic.
EDIT'ed