From the official Japanese Twitter account, Gomamon’s evolution first introduced in the 1998 Pendulum 2.0: Deep Savers virtual pet.

Card NumberBT1-034Level4
Card TypeDigimonPlay Cost5
ColorBlueEvolution Cost2
Digimon TypeMarine AnimalDP5000
Main Effect
Source Effect[During your turn] This Digimon cannot be blocked by your opponent’s Digimon with no Evolution Sources.

Booster 1 launches in Japan on May 15th, 2020.