Regirock

Regirock is a Legendary Pokémon introduced in Pokémon Ruby/Sapphire (2002). It is one of the "Legendary Titans" alongside Regice and Registeel, created by the Mythical Pokémon Regigigas. Regirock is said to have been formed from ancient rocks and has the ability to repair its body by absorbing rocks from its environment. Its design resembles a massive, rugged statue, reflecting its status as a guardian of ancient ruins.

Players must first have Regigigas in their party.

Access the Iron Ruins located in the northern part of Sinnoh.

Interact with the altar inside the ruins to summon Regirock.
Regirock is a single encounter and cannot be found through standard gameplay, making it a rare and sought-after Legendary Pokémon