The Regigigas is a Legendary Pokemon that is a Normal-type. This Legendary Pokemon is first introduced in Generation IV. Regigigas created the Legendary Titans as well. This guide will show you how to catch the Legendary Regigigas.
How to get Legendary Titans
Before you can get Regigigas, you need to get all three Legendary Titans. You need a Regirock, Regice, and Registeel. To catch them, you need the National Pokedex first, which you can get in Sandgem Town.
Go to Route 221 and enter Ramanas Park. Talk to the NPC here and you will be able to trade in your Mysterious Shards for a Discovery Slate. You need 3 Discovery Slates for all 3 Legendary Titans.
Go out to Ramanas Park and enter the first cave you see. Enter the 1st Discovery Slate and you will begin a fight with the Regirock. After defeating the Legendary Titan, keep going until you catch all 3 Pokemon.
How to Get Regigigas
Put all the Legendary Titans in your party and go to Snowpoint City. Keep going north until you reach the Snowpoint Temple. You have to keep going down the staircase until you reach the bottom floor, where Regigigas is waiting.