WARNING: The following contains spoilers for Episode 35 of Digimon Adventure: (2020), "The Glowing Angewomon," now streaming on Crunchyroll.
At this point, Digimon Adventure: (2020) has shattered any semblance of the status quo, with Mega-level Digivolutions arriving only a few episodes into the reboot, and new forms available long before the original timeline. But unfortunately, not everything can be triumphant, and in some cases, keeping the status quo may have been for the better, especially in the case of MarineDevimon.
Appearing in Episode 35, this Devimon variant lives deep underwater, and just like his predecessor is working toward Millenniumon's revival. Unlike the first Devimon, however, he's no threat to our heroes at all, which makes a potentially great battle with high internal and external stakes feel more like an afterthought than anything else.
In the episode, MarineDevimon uses his powerful tentacles to pull Komondomon down to its lair, and immediately sets upon attacking the Digidestined and stealing Kari -- but the Ultimate-level Digimon hardly puts up a fight. Champion-level Tailmon is easily able to tear through its tentacles and rescue Hikari, with the slow corruption of Tailmon by turning her own anger and fear against her proving a much greater threat than MarineDevimon himself -- who just sits off to the side while Tailmon deals with her internal struggle, neither attacking nor defending.
This is particularly odd when you consider that in Digimon Adventure 02, a MarineDevimon was not only able to take a direct attack from Zudomon but simultaneously fend off Angemon and Submarimon as well. While it did take a strategic retreat, it reappeared later and gave both Takeru and Iori's DNA Digivolved Shakkoumon a run for its money in Episode 44, "Dark Sun, Dark Spore." They were able to destroy it eventually, and the battle wasn't given much screen-time, but it was very much portrayed as a "we have to kill them before they can kill us" kind of situation in keeping with the other defeats shown that episode.
In contrast with the high-stakes late-stage threat that the 02 MarineDevimon posed, Adventure: (2020)'s is seriously underwhelming with pitiful-looking attacks. The only reason it seemed to pose any threat at all was the element of surprise, coupled with the dark energy surrounding it that allowed it to (briefly) corrupt Tailmon. But with Hikari there to assist Tailmon, and Greymon able to go to higher levels if need-be, the threat posed by the lone MarineDevimon was quite minimal. Even if it had been smart and continued attacking rather than letting Hikari and Tailmon have their Angewomon-creating heart-to-heart that let them obliterate it in just two attacks, Greymon could have easily kept the bottom-dweller at bay.
So, though we're happy to see the show once again focusing on character development and letting the characters rest between battles, MarineDevimon was one opponent who should have at least taken the entire episode to defeat, rather than just a few minutes in the second half.