Adventure does not deserve anything good after Tri
I believe it is a result of being the most known material of the franchise, to a certain extent, and therefore more prone to a denial of change in something pre-established.
Adventure has a scene that is already known, no one pays much attention to the philosophical content or some feats related to lore, if anyone will talk about power in Digimon Adventure / 02 the most they should remember is the fight between WarGreymon and Black WarGreymon where a Gaia Force was used and it was as big as a mountain, nothing more.
Being Digimon Advenure already known as a not very powerful work, it is more difficult to convince people that have come to know DIgimon Adventure that in fact this series has several quotes of multiversal feats... without them thinking that it is an outlier.
This is why Apocalymon was long the only Low 2-C Adventure Character (considering only the anime), it was the only one with a big feat, in a very important scene and that was something known. But of course, there were still those who considered that Apocalymon was still going to destroy a planet ... and that was already a lot in the past.
The reason is clear, Adventure does not seem to be a series of powerful beings, because to a large extent the scenarios are "terrain" with destruction of houses or buildings, sometimes something bigger, but that is considered something ridiculous, so that in the season finale appears some villain performing a ridiculous universal/multiversal feat so then these feats are considered an outlier.
In Adventure/Adventure Zero Two the Tier 2 feats we have are:
- Fusion between the worlds to create a world of darkness proposed by Vandemon/BelialVandemon;
- Reformatting the Digital World by Dark Masters using a code created by Nanomon;
- Four Holy Beast stabilize the hierarchy of worlds by keeping the worlds separate; if this power weakens the result is the breaking of the dimensional barriers which would lead to a collapse of the hierarchy resulting in a world of nothingness (ie, their power keeps the equilibrium in the world preventing a multiversal collapse);
- Apocalymon can reduce everything to nothing and recreate the worlds
What makes it difficult to make Adventure in Tier 2 is how the Digimon Adventure scenario works for some.
There are those who argue that the only reason the Dark Masters defeated the Four Holy Beast is their weakness for light, and that's totally counter-intuitive with Adventure's lore. What is known is that both light and darkness cancel each other, a strong light nullifies darkness while a strong darkness nullifies the light.
There is a reason why Angewomon managed to vanquish Vandemon, the light of her attached to the other Digimon was stronger than Vandemon. The same ratio of Angemon against Devimon and Holy Angemon vs. Piemon. Their light, sometimes united with that of others, was enough to nullify the opponents' darkness, or enough to weaken the darkness for something to be taken advantage of. If a person of greater power of darkness attacks someone of light power that is less in comparison, the being of light will end up weakening because the darkness will annul the light. But the same works the other way around. If the Dark Masters "defeated" the Four Holy Beast is because their darkness overcame the Four Holy Beast light, and not just for an advantage that makes power irrelevant.
Knowing this, what is missing is to see the situation behind it. We do not have details about the fight between them, we know that it was a long time, caused much damage in the Digital World and that in the end the Four Holy Beast were sealed.
Tailmon says directly that the Dark Masters are the same as the Four Holy Beast, but she also says that her knowledge of the Four Holy Beasts is very small. (She was only able to explain that they are responsible for protecting time and space). that this knowledge was manipulated by the side it was in the fight, which was what opposed the Four Holy Beast, so this knowledge may have been influenced in relation to the Dark Masters being equal to Four Holy Beast.
And finally, what we do know is that in fact the Dark Masters were using the power of Apocalymon without knowing it. If we consider that the Dark Masters used a single power coming from Apocalymon, we can say: Apocalymon >>>>> Dark Masters (2nd round)>=Four Holy Beast>Dark Masters (1nd Round).
BUT, we could also say that the Dark Masters were constantly using power coming from Apocalymon and that this power was slow to flow from the Dark Area to the Digital World, over time this power was canceled with that of the Four Holy Beast and after a long time with the power of Apocalymon weakening the Four Holy Beast was that it was possible for the Dark Masters to seal themselves without really being equal, they just had the feeling of being equal because they did not know of the influence that Apocalymon had on them.
To understand this better, I believe it is good to wait for the next chapters of the novel to be translated. Anyway it's funny with the more complex explanations for why Adventure isn't scaling to Tier 2 feats, they are often more common than the simpler ones that justify the scaling.
Or maybe it's hard for me to understand, when I just want to explain the lore about it without getting too caught up in the limitations of all the rules of power levels and scaling 0v0