i usualy nickname my pokemon something zelda related.
for example my vaporeon is named morpha after the oot water temple boss, i also have a serperior named rope, after the snakes in oos, and a bisharp i named stalfos.
I love nicknaming my pokemon! I usually name my pokemon names from anime or vocaloids like Miku, my shiny Kirlia or Gumi my Gardevoir. Other times I name then after other video game characters or enemies, like Snake my Lucario, Link my Gallade & Tail my Vulpix, JabuJabu my Swampert, Zora my Milotic, Groose my Throh, Amy my Jigglypuff, Daisy my Gloom, Bowser my Emboar...if I keep going, I'm gonna end up making a full page of nicknames
I generally nickname my pokemon, yes. When I first played the Pokemon series I didn't really bother with it, but when I continued to play it, it sorta became a habit with me and now I nickname all of the pokemon I catch except for the rare few that I'm just catching to trade.
I tend to nickname any I plan on training to level 50 or up, and its often based off of their original name or something I saw recently. So my Gallade is named Ian and my Breloom Anthony, because I watched a lot of Smosh that day. all my starters names: Blazy(Blazekin), Plippy(Empoleon), Todd(Feraligatr), Wotts(Samurott), and Midget(Blastoise. He was going to be Squirt, but then I thought, squirt=short=midget!)
As a kid around 9-12 I always thought nicknaming was childish, most of the people who I knew that nicknamed Pokemon nicknamed their Pokemon childish names like: Crap, turd, Butts, stupid,etc. I do nickname them now but I do not nickname them childish things (unless it is a pun).