Skullgreymon is an extremely powerful Dark-type attack Digimon in "Digimon World Dawn." Its appearance is that of a large dragon's skeleton, and it uses its immense power to overwhelm other Digimon in battle. You first encounter a Skullgreymon in the Shadow Abyss, near the end of the game. Skullgreymon can be hatched from Kaizer Eggs and Nightmare Eggs, which you can create by matching the appropriate Digimon to have them mate. Hatching a Skullgreymon is a lengthy process, but the reward is worth the effort.
Play through the game until you encounter the Skullgreymon in the Shadow Abyss. This happens automatically, since the Skullgreymon is part of the storyline. When you encounter it, scan it to get its data stored.
Match your Digimon with one on another DS, using either "Digimon World Dawn" or "Digimon World Dusk," to create either a Kaizer Egg or Nightmare Egg.
Return to the DigiColiseum and speak with the Kudamon behind the counter. He walks you through the process for getting online to match your Digimon with someone else's. To create a Kaizer Egg, you need a Dragon-type Digimon and a Dark-type Digimon that are both level 40 or higher. To create a Nightmare Egg, you need Vilemon and any Dark-type Digimon with a Spirit level of 150 or more. Follow the onscreen instructions to connect to the second Nintendo DS and match the two Digimon to create an egg.
Travel to your farm to tend to the egg. The Nightmare Egg needs 800 or more Dark Experience, and the Kaizer Egg 1,200 or more Dark Experience, before hatching. Additionally, the Kaizer Egg needs to be level 15 or higher, and the Nightmare Egg must have a Spirit level of 160 or higher, before hatching.
Purchase any Farm Goods you need from shops throughout the game. There are shops in most cities with a special section for Digimon Farm Goods. Check the inventories for items that raise Spirit, such as Book Shelf, Study Table and Pentagram, and items that raise Dark Experience, such as Broth of Darkness, Cursed Chest and Dark Tower . When you travel back to your farm, you are given the option to install these items there so that the egg can train before it hatches.
Read the Digimon Farm reports you get from Calumon. These will explain how close your eggs are to meeting the requirements for hatching. Travel back to the farm when they have met the requirements and save your game. Both eggs have a 33 per cent chance of becoming Skullgreymon, so if you don't get one after interacting with the egg to make it hatch, reload the game from that save data and interact with the egg again until you get a Skullgreymon.