Quoted By:
They get names that fit them and their characters (that I make up).
I have a naming theme for some pokemon though. My starter in most games gets named after WCW nWo members, but somtimes with some changed letters so it's still an "original" name. Charizard was Hall, Feraligatr was Lesch, Venusaur in pic related is Sogan, and Emboar was Sting.
Every first Magikarp I catch gets some variation of BOOKER, always in caps.