I was thinking recently about how certain Digimon from the anime canon came to become part of the mainline canon. In particular, why do Omnimon and Gallantmon exist outside of Adventure and Tamers respectively? We know they do, they're two of the most well known Royal Knights, who seem contractually obliged to show up in everything despite usually being the worst thing about whatever they're in. But if you look at how they both came to be in those respective canons (which is more or less where they debuted) it's hard to see how they could exist as a 'species' and not as a creation unique to those two series'.
Yeah, we all know the real reason is because they're marketable, but I'm more interested in the stretch of logic needed to accommodate them. Take Omnimon for example; he can only exist as a fusion of WarGreymon and MetalGarurumon. In Adventure, that's because they were the two strongest main Digimon, belonging to the two leads who had dramatic chemistry with each other. Omnimon makes perfect sense as a culmination of that duo. But in other continuities where Tai and Matt don't exist, Omnimon's existence becomes a contrivance. You can't hide his heads for hands, so it either gets ignored or there has to be a pairing of Agumon and Gabumon in every continuity featuring him. Cyber Sleuth is a good recent example of this; the story goes that Omnimon started as himself, but then had to unmerge to enter Eden, leading to the Agumon and Gabumon who were close to each other but didn't quite understand why. Does that mean even ones who start at the top have an Agumon and a Gabumon as their "base"? I know there's a chicken and egg question in here somewhere.
Gallantmon is even worse. Agumon and Gabumon are at least numerous enough that you could justify their fusion being a 'species' rather than an Adventure-specific character. But Guilmon is literally an OC. He was drawn by a human kid and his top form (the one in the Royal Knights) came to exist when he merged with that kid. It's weird that he became his own species, especially when other characters and concepts unique to Tamers didn't. Hell, I'd buy Calumon, the Gnomes and even the D-Reaper as having multiple incarnations across different canons more than I would Guilmon, since they shared a point of origin with the rest of the Digimon in that series, whereas Guilmon is totally unique.
What does everyone think?