Diaboromon: Digivolve an Okuwamon (ultimate form of Kunemon) with 20+ DP to mega.

Baihumon: Digivolve a Meteormon (ultimate form of Gotsumon) with 20+ DP to mega.

Omnimon: Digivolve a Metalgreymon (ultimate form of Agumon) with 20+ DP to mega.

It will take a long time to obtain the DP, but it is worth it in the end as all of the Digimon are very powerful!

Note: Dp = Digivolution Points.