Some other fraction of them are memes
*chanting*
Slaking named Harambe, Slaking named Harambe, Slaking named Harambe
Anywayyysss...
I nickname any Pokemon I use. I've said it before, but I've never had a Pokemon on my team that I haven't nicknamed. It just feels weird.
That being said, I typically go with names that come from nature, names that are colors, or names that are pretty and whimsical but that I would probably never hear on a human (Whisper, Incyndia, Revery, etc)
Some examples:
Grass Types - Meadow, Juniper, Ivy, Emerald, Rosetta
Water Types - Aquarius, Crest, Azure, River, Cydon (short for Poseidon)
Ghost/
Psychic Types - Violet, Magica, Revery, Whisper, Muse
Fire Types - Incyndia, Ginger, Singe, Charise (Similar to Charcoal, but more feminine)