How do you get Ditto without beating the Elite Four in Pokemon Emerald?

its a secret but i will tell because im cool. Ok listen up, go to Fallarbor Town where the kid gives you dig then teach it to a Pokemon. Go through the door in his house, go all the way to the back where the man is...Use DIG and a door will open. Go in SAVE!!!! Because the Pokemon in there are at the level 70's.