K, lets say you were EV training a Gengar.
First breed A TON of gastly and hatch the eggs. Then look for any gastly with Modest,Mild or rash nature so you can get good Sp. Go here for all natures.
http://www.serebii.net/games/natures.shtml
Then once you find the best one, give it a cool name. :)
Then for Gengar you have to give it 10 Carbos and 10 Calcium.
Then you would put on a power item an give it pokerus.
Ok, now im bored. Go Poo and then go to
http://www.YouTube.com/watch?v=Jch784-3QUQ
Train it as you train all pokemon.
It's pretty obvious... EV train (I suggest EV Training in Defense)...
No
train them without using rare candy's
yes.. you can