How do you get reggigas in Pokemon Diamond?

You have to migrate the three regis from Pokemon ruby/Sapphire/emerald (doesn't matter which) and go to snowpoint city. go north to the temple and now you can get in after you beat either the gym leader or the elite 4. go through the puzzle and on the 4 or 5 floor he is in the middle at lvl 70 and go up to him and press a