Regice

Regice is a Legendary Pokémon introduced in Pokémon Ruby/Sapphire (2002). It is one of the "Legendary Titans" alongside Regirock and Registeel, created by the Mythical Pokémon Regigigas. Regice is said to be formed from ice dating back to the Ice Age, with a body so cold (-200°C) that even magma cannot melt it. It is often depicted as a guardian of ancient icy ruins.

Players must first have Regigigas in their party.

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

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