As I am a shiny hunter, I only nickname my shiny mons. As my shiny mons are 117 I will not write 117 nicknames, I will write only my favourite ones:
Falistra, the shiny Eelektross: I'm italian, so I give a lot of italian words as nicknames for my Pokemon. "Falistra" is an italian archaic form for "Lightning" because Lightning in italian is "Fulmine" but it was extremely common in italian nicknames for electric pokemons.
Leonida, the shiny Chesnaught: is the name of a greek hero (I think everyone here has senn the film "300")
Vespiore, the shiny Volcarona: this is a bit complicated because is the composition of two italian words: "vespa" and "fiore" that mean "wasp" and "flower"
Nutella, the shiny Golem: I don't know why but I love it
Ombra, the shiny Umbreon: "ombra" is the italian of "shadow"
Cianuro, the shiny Dragalge: "cianuro" is the italian for "cyanide". I think it is obvious why
Dovahkiin, the shiny Sylveon: who played Skyrim knows why
Muliphain, the shiny Charizard: it's the name of a star that means "star to swear on"
Tentazione, the shiny Aegislash: is the italian for "temptation"
Cersei, the shiny female Pyroar: who likes GoT knows why
Aurora, the shiny Suicune: this is the same in english and italian so there is no problem
Lilleraldo, the shiny Blastoise: is a composition ofd two italian words: "Lilla" and "smeraldo" that mean "lilac" and "emerald" because of the shiny colors of blastoise