How to Find it
In EO2, during the Be the Best Trainer quest, you will notice one mission marked, "Dolphin in the Stone Caves." You will go to the Cavern of the Gods in the Celestial Mausoleum and notice a Commerson's Dophin with markings that appear to be a sure sign that this is a different dolphin.
All these things you can use for offerings are found from Nancy. You will buy everything the "Other" category, except for the Seafood and Squid food and the toy orca, which are used for the Orca and Risso's Dolphin partners, and bring them to the Pacifca Treasure.
You present these items one by one, and after presenting everything you have, the Commerson's Dolphin will be your partner and you will recieve a title, "Great Oracle."It will now come to you when you ring the bell on [[Nineball Island|Nineball Island]].