It sounds like you're looking for the for a Digimon Adventure game — likely the PSP title "Digimon Adventure" (2013), which is a turn-based RPG covering the events of the first anime series.
The ISO Digimon are led by the powerful and enigmatic , who seeks to merge the Digital World with the human world. The Chosen Ones and their Digimon partners must battle against the ISO Digimon to prevent this catastrophe.
Released exclusively in Japan in 2013, Digimon Adventure is not just another licensed beat-'em-up. It is a full-blown, turn-based JRPG that retells the entire first season of the anime (The Eight Chosen Children) with stunning fidelity. For Western fans, accessing this game has always been a challenge due to its region-locked release and Japanese-only text—until the fan translation community stepped in.
If you own a hacked PS Vita, you can copy your patched ISO to ux0:pspemu/ISO/ . Playing the English translation on original Sony hardware (via Adrenaline) is arguably the purest experience, as the OLED screen of the Vita makes the colors pop exactly as the developers intended.
and a special post-game "Sub-Episode" featuring protagonists from later seasons like Digimon Adventure 02 Digimon Tamers