Any digimon has the potential to be good, it just depends how you raise them. You can always convert your scan data for a bunch of digimon and check out their stats and future digivolutions.
In my opinion, dark digimon really develop well with good moves.
So it's really up to you, but you can also get different types so you have a good balanced team.
Since you have one holy, 2 dark types, you can check out any dragon, bird, insect, beast, machine.
One digimon I have was pretty much my trump card is VenomMyotismon. Though, he's a dark. (Pagumon to DemiDevimon, to Devimon, to Myotismon, then VenomMyotismon)
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