Because if you don't, you won't know what to do at the end of the game.
No!
yes
You get someones friend code -Pokemon Master
get a pal pad and go to add friend
you have to trade with a friend.
4941 7759 4313
YOU DON'T!You get it from a friend with Diamond version
Your friend-code is loacted in the Pal Pad which you can get from the bottom floor of any Pokemon Center
Just google it or ask a friend
They must already have it and then have them use it then have them attach it to a Pokemon and then make the trade you the Pokemon.
trade with a friend or action replay
In Cerulean City in Kanto