I don't think you can get regirock in pokemon ruby.
There is no cave for the regis in Pokemon ruby. I have the game no regice regirock or steel.
It's different in different versions.
You go into a underwater place where theres braille then have a wailord at the top of you party and a relecanth athe bottom then hey presto you have opened all the caves.
in ruby, sapphire, and emerald, regirock is in the cave in desert ruins. to get it in firered or leafgreen, u have to trade it from ruby, sapphire, or emerald. To acsess them you must have a waillord and relicanth oh and dig. surf down the bottom of pacifalodg town
rayquaza on top of sky pilair, regirock in the desert, groundon in the cave of origin
I think you need certain pokemon and dive to get to it. when you get to the cave, you must walk a certain pattern
in ruby there's groudon, raquaza, regirock, (if you consider it a lengendary) regice, and regirock
It means that the three doors are to Regice, Regirock, and Registeel.
Groudon is at Cave of Origin,Regirock is at Desert Ruins,Regice is at Island Cave,Registeel is at Ancient Tomb,Latias is in the wild in hoenn,and Latios is in Southern Island.
You know where the dessert is? Go there, go in the middle of it, now go all the way down. Before you get to go all the way down, go to the cave. Talk to the middle paper. It says... Go right 2 steps, now go down two steps. USE STRENGTH TO OPEN THE DOOR! You'd open the door, go in the door. There lies Regirock.
to get regirock in Pokemon platinum, you have to upload it from ruby, Sapphire, or emerald.
I don't think you can, in emerald you need the nationaldex and POW! it's open but in ruby and sapphire you can't.