I have the same nicknaming habit. Always trying to outdo myself... It used to be just fitting words and such that sounded cool, then the generic mythological figures, then it became Mario characters (like in ASB!), then general video game characters, then in Black I started naming the new Pokemon what I felt their names should have been (Oshawott named Wotter, Blitzle named Zapra, female Swanna named Swancess, etc.).

I'm going to go with stupid puns on this run through. My Haxorus shall be named Leet, just to be gloriously unoriginal.