Damaging opponents or taking hits fills an evolution meter. Once full, pressing the R1 button allows Rookie Digimon to "Digivolve" into their more powerful Ultimate/Mega forms for a limited time.
Hidden characters like Black WarGreymon , Impmon (to Beelzebumon Blast Mode), and Omegamon can be earned by completing specific challenges in Story Mode. Digimon Tamers Battle Evolution
Digimon Cards occasionally fall onto the field. Players can pick these up to trigger elemental attacks or instantly boost their evolution gauge. Damaging opponents or taking hits fills an evolution meter