There are 7 types of Digimons you can choose from when making a new character. Gigimon, Gummymon and Viximon are the basic choices; Yamon, DemiVeemon, Dorimon and Hopmon can be chosen after you take part in special in-game events. These are your partner Digimons who fight in your Digimon field battles.
These are Digimons captured on your adventures in the Digimon
Captured Digimons join in battles only when your partner Digimon recalls them.
You can open your list of Digimons (keyboard shortcut L) and switch a captured Digimon with your current partner.
There are enemy Digimons that you meet on your journeys.
You can get more details about digimons by clicking HERE