Well I think, that Armor Evolution could be handled in 2 ways:
1)
Some form of evolution stones.
Therefore, Veemon for example could evolve to one of the following:
Flamedramon (Courage), Raidramon (Friendship), Sethmon (Love), Honeybeemon Knowledge), Depthmon (Reliability), Yasyamon Sincerity), Sagittarimon (Hope), Gargoylemon (Light), Kangarumon (Kindness), Magnamon (Miracles), GoldVeedramon (Destiny)
Some of those have "Main" Evolution paths(Flamedramon->Majiramon, Raidramon->Caturamon. Sagittarimon -> Indramon), while others have just a list of possible evolutions.
So basically, the armor evolutions(besides Miracles and Destiny, those are pretty much Mega level) could be treated as Champion type and then evolve into the corresponding Ultimate type and finally into a Mega as well.
2)
Kind of like Summon Attacks, that summon the Armor Form, attack and then get a cooldown for a few turns.
I'd rather see the first option, because the "summon attack"(if you guys want to do that) could be handled with Digimemories(for more information about Digimemories watch Digimon Xwars, or play Digimon World Re:Digitize)
About the Goblimon question:
The main evolution is Ogremon and from there, you pretty much have a huge list of optional evolutions:
Jogress Evolution:
SkullSatamon (w/ Devimon), Divermon (w/ Mantaraymon)
Normal:
Andromon, Asuramon, Mummymon, Minotarumon, Zudomon, BlackWarGrowlmon, Mephistomon, Matadormon, Arukenimon, Etemon, Garbagemon, Giromon, Jagamon, NeoDevimon, WereGarurumon, Whamon Ultimate, Vademon, WereGarurumon (X), Kabuterimon, Pandamon, WaruMonzaemon, Indramon
So this pretty much depends on if they want Etemon to be one of his Ultimates, or not. But it would be possible ^^
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