How do you get dialga to come back in pokemon diamond?

My son is playing Pokemon Diamond and was at the spot where he ran in the battle with Dialga and now Dialga is gone. Is there anyway to make him return?|||the only way you can do it again......is if you buy an ACTION REPLAY DS.............and then go to the manager when you install it on ur computer.............and click on UK CHEATS.......u may be in the US but this is the only way u can do it.........you click on that and then it says a whole bunch of cheats look for the one in diamond that says catch all pokemon or something like that|||I'm sorry, he has to start the game all over again, or get a Dialga from somebody else (Wifi)





If he has an Action Replay, (hacking device), then he can use a cheat code to re battle Dialga.





That's the best advice I can give to you and your son.|||Your son should have saved before battling. Then he could of caught it. Sorry but there is no way he can get Dialga back. Unless someone trades him a Dialga or he starts the game over.|||lol well one of the first rules of playing pokemon is SAVING before you go into important spots so an answer to your question is no he cant get it back better luck next time|||Only to start the game over-- sorry. But I wouldn't. Unless you trade all the faves to a friend and make them give them back afterwords.|||nope, if u defeat/capture a legendary PKMN, it won't appear again.|||nope unless he starts the game over|||Nope. That is the only time he appears.