>>53719234So we are reaching a point where "too many monsters" is a problem. Let's hope that gen 10 will never exist then.
For the evolutions, Digimon are not biological creatures. Every Digimon is a state and they go from one state to another in the next or previous stage, depending of their stats, personality and education. Patamon evolved into Angemon because he was pure of heart and fought against the devil. You have some stronger line like the Agumon->Greymon (seen by the fact that Agumon X shows the Greymon-species data and not another evolution), but if raised in a certain way, other evolutions can occurs because he would have more checked contitions for them (Centarumon if he is wise, Tyrannomon if he has a strong defense etc.)
The sense of surprise and the fact that you can play with a similar Digimon for different results is what make it fun. Tyrogue was nice to raise, but they never tried something similar since.