Skript to change nick on tab, above player - nametag and chat. Support for colors!
For Tablist go to my skript: https://www.spigotmc.org/resources/tablist-skript.91236/

Commands:
/chnick <text> - to change your nickname, example: /chnick &2Dan Kuso
/chnickso <player> <text> - to change someone's nickname
/chreset - to reset your nickname to default
/chresetso <player> - to reset someone's nickname to default

Requirements:
Skript
Tablisknu
ProtocolLib