How do you get mesprit in pokemon diamond?

go to the poketch company and talk to the owner on the first floor. he gives you the marking map. for an easy way, go between route 210 and route 215 walking back and forth until mesprit goes to the gr on route 210 I dont know why but mesprit will go on that route even while you're on it. catch a bronzong at turnback cave. heart scale it in pastoria city to give it block and hypnosis andthen give it a quick claw. try and block mesprit then damage it to like yellow, then switch to a false swiper to get it to 1 hp. do the same thing to encounter mesprit again and block it but this time use hypnosis then go with ultra .