Okay, here it is
Regi Steel
To find Regi steel you have to go to route 120 and find a stone mound. There will be a doorway. Now, go to the centre of the room and use Fly. A door will then appear in the wall. Walk in and, you will see Regi Steel. Save before you battle it and, bring a lot of Ultra balls and timer balls, and try to get it to sleep or paralysed.That is the same for all of the regis.
Regi Rock
Go to the desert by Lavaridge and go down to the bottom where you will find Regi rock. Walk up to the braille at the front and go three steps down, two steps right and then, use strength. The door will open and do the same as you did to catch Registeel.
Sorry, I don?t know how to get the last one.