>>33413485Also keep in mind that every single Digimon on this chart can also digivolve FROM a bunch of entirely different shit not pictured. This follows all the different things one baby mon can turn into, but other things can digivolve into many of the same things and sort of cross over their evolution lines.
In the shows they almost exclusively just have the digimon character follow through one evolutionary line that is designed to fit together for marketing purposes, but you're not really supposed to look as Greymon as just what Agumon evolves into, rather, Greymon is one of a massive pool of champion-level Digimon, that many Rookies, one of which is Agumon, can become.
The ascension of power in a monster catching game is similar in this way to SMT, where there isn't really any cohesion of design as the monster becomes more powerful, and there are many ways to reach the same result. In SMT you're fusing things rather than evolving them though, and the hierarchy is determined by base-level rather than split into evolutionary stages.