How can you meet Choas Grimmon in Digimon World Dawn?

You cannot meet Chaos Grimmon in Digimon World Dawn, or any other Digimon World game for that matter. Chaos Grimmon is a powerful Digimon from the Digimon Adventure 02 anime series.

Chaos Grimmon is not a playable character in any of the Digimon World games.

While there may be other powerful Digimon you can encounter and battle in Digimon World Dawn, you won't find Chaos Grimmon in the game.