Xros Wars takes place simultaneously before and after everything else in the franchise. It has always been Diaboromon!
The first Greymon happened when an Agumon killed a Kabuterimon and put its head on as a helmet, providing the data necessary for evolution.
The spirits from Frontier are incomplete digicores.
Gabumon’s pelt is made of fur it collects from Garurumon. It evolves when it collects enough.
Megidramon and Chaos Gallantmon are the same digimon. What you see is dependent on how it scares you pissless.
Jo’s Gomamon cannot be asked to do anything if left to his own devices. He needs someone as high-strung as Jo to motivate him.
All of the Warrior Ten died fighting Lucemon and his armies except Ancient Greymon and Ancient Garurumon.
The fusion spirit of darkness, Reichmon, can turn off physics to mess you up.
Imperialdramon Black is what happens when the insect data in Paildramon overtakes the dragon data during evolution, turning it into a mindless killing machine.
When a digimon dies, its soul is judged by Anubismon. If it is good, it is reborn as a digitama. If it is evil, it gets sent to the realm of the dead, where it is probably destined to be eaten by Plutomon.