To make the quest go as smoothly as possible, these preparations should be made:
- A Pokémon with Surf or a Surf mount
- A full team of Ice type Pokémon
- A Glalie with 70 or less total IVs
- A Pokémon with Flash
The Eternal Stone fragments
Head to Vermilion City's Library to begin the quest. In the utmost top-right corner of the library, there is a bookshelf with a book you need to read. It tells the legend of the Eternal Stone from Shoal Cave. The book states that the stone was unbreakable by any trainer that tried and that only the heat from [Groudon]] from its legendary battle with Kyogre was able to break the stone into four fragments, each hidden away in separate locations by trainers. The stones were hidden at Ice Path, Lake Acuity, and Seafoam Islands.
From here, you'll need to gather all fragments that were hidden away. There is no particular order to do these in. Travel to each of the locations listed above and look for the fragment among the large rocks. The exact locations are shown below.
The text you see from the stones will be hints that help you get the fragment, however, the hints are written in Morse Code.
For the fragment in Seafoam Islands, you will need a Pokémon with Flash in your party to receive the fragment.
For the fragment in Ice Path, you will need to wait about 25 real-life seconds then interact with the stone again to get the fragment.
For the fragment in Lake Acuity, you will need surf counterclockwise through the edge of the lake. Once you complete an entire lap, you will get dialog telling you to interact with the stone again and, after doing so, you will receive the fragment.
Combining the fragments
After gathering the three fragments, you will need to gat the fourth and final fragment from Shoal Cave. For this fragment, you will need a Glalie with 70 or less total IVs and place it in your 6th party slot. After you've gotten your Glalie ready, head to the Low Tide Ice Room inside Shoal Cave. Interact with the large rock there and you will receive the final fragment.
With all fragments attained, you now need an expert on the subject. Make your way to Pewter City's Museum and speak with Scientist Paul. He will tell you that combining the fragments is possible, but you need to show him "cold" Pokémon. Bring him a full team of Ice type Pokémon and he will fuse the fragments together, forming the Glalitite, which he will then give you.