2:18 pokeradar... Also dont run away from it ou the chain will break. (Go for the bushes that shine and look like water sprinklers) So just kill off pokemon till toi see a ditto. Whcih ditto's will keep poping up more. It took me 45 minutes to find one so be patient.
toi Can find Ditto in Diamond on Route 218 but toi need the PokeRadar,to get the radar toi go to Professor Rowan after you've seen every Pokemon in the Sinnoh and Defeated the Elite Four ;)