Doesn't nickname them
Shuichi
Hajime
Peko
Junko
Izuru
Nagisa
Maki
Nicknames them after something with historical/mythological/forgein/deep meaning
Korekiyo
Rantaro
Yasuhiro
Toko
Kyoko
Gundam
Monaca
Angie
Nickname them after memes
Kokichi
Kazuichi
Leon
Ibuki
Masaru
Miu
Nickname them after somebody they know
Makoto
Mondo
Sakura
Hina
Teruteru
Hiyoko
Nagito
Komaru
Kaede
Tenko
Kaito
Nickname them random things that they like
Sayaka
Chihiro
Akane
Kotoko
Himiko
Give them human names
Taka
Mikan
Jataro
Gonta
Give them nicknames that actually fucking make sense
Mukuro
Mahiru
Fuyuhiko
Name them after characters from other franchises
Hifumi
Chiaki
Tsumugi
Doesn't play Pokèmon
Celeste
Byakuya
Twogami
Nekomaru
Ryoma
Kirumi
If you don't agree, then tough shit it's my list. Change it if you want