How To Obtain Omnimon
All you have to do is get a Wargreymon and Metalgarurmon to level 68 with a friendship of 100% and a speed of 415.
How To Obtain Chronomon HM
If you already have a Susanoomon and Varoduromon and have beaten the Legendary tamers quest you need to get both to LVL. 83 with a high amount of Holy Exp.