hmmmmm I have a couple good ones actually (and I know this is from like 4 years ago but I want these names rated.)
Greninja I named Narutoad. I love it cause it's a pun and I think it reflects his ninja self
Gallade I called Zoro. When it goes mega, it gains kind of a Zoro mask. Also it sounds cool
Heracross is Jaime. Because the superhero Blue Beetle's real name is Jaime Reyes. And Heracross is a blue beetle
And finally, my last good nickname I think, is Houndoom. I named Houndoom, although it has one head, Cerberus because it's an awesome nickname and it is kind of an unholy dog.