Most likely.
I don't think you can get regirock in pokemon ruby.
These Pokemon can be found before the National Dex: Latias (Alpha Sapphire), Latios (Omega Ruby), Kyogre (Alpha Sapphire), Groudon (Omega Ruby), Regirock, Regice, and Registeel. These Pokemon can only be obtained in the Delta Episode: Rayquaza and Deoxys. Post-National Dex Legendary Pokemon are: Regigigas, Ho-Oh (Omega Ruby), Lugia (Alpha Sapphire), Heatran, Mesprit, Uxie, Axelf, Palkia (Omega Ruby), Dialga (Alpha Sapphire), Giratina, Cobalion, Terrakion, Virizion, Reshiram (Omega Ruby), Zekrom (Alpha Sapphire), Kyurem, Raikou, Entei, Suicune, Tornadus (Omega Ruby), Thundurus (Alpha Sapphire), Landorus, and Cresselia.
in ruby there's groudon, raquaza, regirock, (if you consider it a lengendary) regice, and regirock
to get regirock in Pokemon platinum, you have to upload it from ruby, Sapphire, or emerald.
You can only get Regirock by transferring a Regirock from Pokemon Ruby, Saphire, or Emerald to the Pal Park I believe.
You'll have to trade Regirock from Ruby, Sapphire, or Emerald.You get a regeirock by trading it from ruby sapphire or emerald. that's how you get it to fire red.
Illumise in Pokemon Omega Ruby can be caught in Zorua at the park.
In Diamond you can't catch Regirock, you have to migrate it from Pokemon Ruby, Sapphire, or Emerald.
You cannot get Regirock in Diamond without migrating one from Ruby, Sapphire or Emerald.
You can find him in the lower regions of the desert
Regirock