you have to eat a pickachu fsdfsfds gbfrbyf
You Can Go By The Pokemon Name Rater
You can go to the name rater in Lavender.
The name rater is in Agate village in both Colosseum and XD
the name rater or "nickname man" is in lavender town.
Go to Eterna City and go into the building, that has the Name Rater on the sign. Talk to the old dude at the table and he will "rate" your pokemon's nickname and ask if you want to change it. You cannot change a traded pokemon's nickname.
if you want name rater hes in eterna city
when you first catch a Pokemon you can give it a nickname but if you want to change its nickname then you need to go to slateport city and talk to the nickname rater (he will change the name of any of you Pokemon that are in your party)
After you catch, hatch, or receive a Pokemon as a in-game gift, you'll be asked if you want to nickname the Pokemon. You can also nickname a Pokemon by going to the Name Rater; where it is depends on the game you're playing.
There is a man in Slateport that will change your pokemon's name.
You change your pokemon's nickname at the Name Rater, who has a house located in Castelia city
The Name Rater in a house in Lavender Town can change your non-traded Pokemon's nickname.
same place in diamond/pearl, in Jubilife City