I named my Gengar Hendrix, lmao. When I caught it as a Ghasty I named it PURPL HAZE or something, but that looked dumb so I changed it to Hendrix.
Other nicknames really depend on what I'm doing at the time, lol. Like if I'm listening to music or something.
Torterra - Ultrabrite (The brand of toothpaste I use :D)
Donphan - Conrad (I had just seen Bye Bye Birdie)
Steelix - Bustello (song I was listening to)
Dunsparce - Marimba (I was putting off practicing for band, lmao)
Ledian - Silver (In rememberance of the shiny one I failed to catch in Silver )
Cherubi - Mary Jane (Because it's number is 420 lmao)
Delibird - Oscar (Don't they just look like an Oscar?