>>712346732digimon as a whole? on one hand you have the v-pets where you raise them, they battle and grow, and they evolve.
on the other hand, you have the anime's take, where they become partners with a human, either because they're linked by fate or because they just choose to stay together. the biggest aspect of this bond is probably how digimon feed on human emotions to reach higher stages.
as for games, one of the most prominent features is evolving and reverting to previous stages for various reasons (e.g. lifespan, level caps, to branch out into a different evo (and possibly inherit skills), to raise a stat that increases when you evolve/devolve, to fuse them with another mon)
as for the story games in particular, they have plenty of defining features
>scan as you fight. each digimon of a species raises a gauge. if you reach at least 100%, you can produce your own copy. the higher the number, the stronger it will start out (it's not )>uneven turn list. units don't act every round. some may take multiple turns in one>the digi-farm system. your idle mons actually spend their days on a farm, doing training stats, gaining exp, digging for items, finding cash, developing new items or training machines, etc.those are the main things that come to mind, but other games have their own pecularities (e.g. the lane system in the DS rpgs that was scrapped later, the combo system in cyber sluts)