In Yellow, I named him "Purple", I don't know why, I think that was my favorite color at the time, I can;t really remember, I was only five. I had to go back today and check it to see what the name was.
In Gold and Crystal both, I named him Idiot, because he ticked me off during the beginning of the game, and it was the best name I could think of for someone like him. Looking back, I would have named him "Ginger".