The gameplay revolves around raising a single Digimon from its egg form, hatching into a Fresh, up through In-Training, Rookie, Champion, and with work, Ultimate. A Digimon partner will "fade away" with age, and return to an egg eventually, so the player has to raise it again.
To raise a Digimon partner, the player must train it, feed it, let it rest, and take it to bathrooms. Training is done to increase the Digimon's stats to make it stronger in battle. Raising a Digimon well will result in the Rookie Digimon "Digivolving" into a Champion form with better stats, while not training or raising it well will cause it to Digivolve into Numemon, a Champion Digimon with inferior stats and skills.