you will need Relicanth (Rare but is around sootopolis under water), and Wailord (Evolve wailmer at 40) and a Pokemon that knows dig . go to pacificlog then surf left if you do it right you will find a dive location dive, go down, then resurface at the brail on the wall.. once at the cave go up to the brail and use dig. then walk up. put relicanth first Wailord last. read the brail and an earthquak relesis the pokimon. Regice: read brail do nothing for1-2 min. door will open. Regirock: go to brail then right right down down then use strenght. Rigisteel: Go to middle of cave then use Fly. Save in front of each one so if you make them faint just restart. I caught them all with about 50 ultra balls. it helps to catch it If you press A and down at the same time and hold while you through the ball. releace when ball opens then, when it closes press B and down and hold until you catch it. or rapidly press A and select at the same time. ive used both with mixed results but they help a little.
In Diamond you can't catch Regirock, you have to migrate it from Pokemon Ruby, Sapphire, or Emerald.
I think you need certain pokemon and dive to get to it. when you get to the cave, you must walk a certain pattern
Regirock, and finally Registeel.
u have to migrate them from ruby Sapphire emerald
you import it from em/ruby/saph and catch it in pal park
I don't think you can get regirock in pokemon ruby.
You can only get a regice, regirock, and a registeel by migrating them from ruby or Sapphire. If you migrtate these Pokemon you can also catch regigigas.
You can catch Groudon,Rayquaza,Latios,Deoxys,Celebi,Jirachi,regiice,regirock,registeel,and Mew
to get regirock in Pokemon platinum, you have to upload it from ruby, Sapphire, or emerald.
you need regice, regirock, and registeel from Saphire/Ruby/Emeraled
The legendaries you can catch in Pokemon Ruby without trading or going to an event are Groundon, Rayquaza, Latios, Regice, Regirock, and Registeel.
latios and groudon from what i know and some how the elite four's dragon master has a salamance oh and trapinch evolves in to flygon