Question

How do you get Regirock, Regice, and Registeel in FireRed/LeafGreen?

Answer 1

Regirock, Regice and Registeel cannot be caught in FR/LG. You would have to trade from Ruby/Sapphire or Emerald.

Comments

You can't trade from Ruby/Sapphire/Emerald to Leaf-Green cause they arent on the Pokédex.

---

Once you get the hoenn dex, you can obtain the regi-trio. I saw a friend of mine obtained them in his firered version.