All Digimon belong to one of 3 types: Virus, Vaccine, and Data. Each type has different skills that are available. A balanced amount of each Digimon type will be encountered throughout the game. Types have a large influence on DNA Digivolving.
A common element of Virus Digimon is attacks that drain an opponent's HP and MP.
A common element of Vaccine Digimon is their Assist abilities to heal themselves and their allies.
A common element of Data Digimon is attacks that give opponents negative modifiers like stat reductions or poisoning.