Oblivion's Valley belongs to Adventure Island, 5 mococo seeds can be found on the island, Island Token drops from the Boss of the island.
Location Oblivion's Valley
Oblivion's Valley is in dangerous waters, don't swim to the island too early, wait for the island to appear.
Oblivion's Isle Token
To get the Island Token, you need to kill the Boss in the center of Oblivion's Valley. At the beginning of the fight, the Boss is invulnerable, to kill the boss you need to destroy 3 bushes around the boss.
Oblivion's Valley Mokoko
You can find 5 mococo seeds on the island, to get 2 mococos outside the map, you need to kill the boss, then go to the place indicated on the map and destroy the round stone blocking the entrance to the mococo seeds.