Some of my favorite nicknames I have done are:
Excadrill: Broom (sweeps like a broom!)
Gliscor: Gator (Gator don't take no ****!- The Other Guys)
Mienshao: Lee Sin (League of Legends character)
Vanilluxe: Brewster (Ice cream company)
That's about all the ones I'm allowed to say haha I'm not that creative when it comes to nicknames so I don't nickname many of my Pokemon.