>>32934011Digimon fan here. I can tell you exactly what went wrong.
Pokemon succeeded because by design, the games forced you to socialize. You wanted to complete your Pokedex, but you only had Blue? Better make a friend who has Red. Forcing that community aspect into it helped prolong interest and give Pokemon a competitive scene.
Digimon games are largely played solo, and only the early ones had multiplayer options; Next Order, which came out not long ago, has no multiplayer at all. Also, Pokemon games are always on portable consoles, while Digimon have almost always been on home consoles. If you wanted to fight your Digimon in DW1, you had to go to your friend's place with your PlayStation memory card.
How the two brands evolved since they first came out is pretty close to Mario games vs. Sonic games; Pokemon (Mario) refined what was already good while adding new stuff, while Digimon (Sonic) kept trying to remake itself into a bunch of wildly different things in order to stay relevant, never truly honing in on what people actually liked about it.