By finding them in the wild, evolving, or trading...
fairly simple
it tells you how to unlock the regis
You can get a rigirock on Pokemon Emerald in the Desert Ruins.But you need to unlock the Rigi's though,before you can attempt this.
you cant
You can get a Rigisteel on Pokemon Emerald in the Ancient Tomb,which is on Route 120.But you need to unlock the Rigi's before you can attempt this.
it's impossible
hoenn region.
Find the key at a under water cave
watch "how to get the three regi's" on youtube
No, the only way to get them is to migrate them from R/S or Emerald.
Go to this link for all you need to know and its a great site for all Pokemon info and its not some stupid website its really good http://www.psypokes.com/emerald/legendaries.php
do the thing to open the other regis do the thing to open the other regis
very sorry but that's impossible you must unlock battle tower