The first Digimon game I remember playing was Digimon World 4, and the second one was Digimon World: Data Squad. I remember playing as Dorumon in the former game, and not getting that far in the latter game, though I saw my brother get way further into the game than me.
Did you see him get Numemon? That Digimon seems infamous for digivolving into if you don’t know the game much.