I've been thinking about that recently. Building Digimon racial templates shouldn't be too hard; the tricky parts are: human–Digimon interactions, caretaking, and evolution.
To recap, the fundamentals of the Digimon franchise ignoring Frontier
• humans partner up with one (or more) Digimon
• partner Digimon are sapient, have a personality of their own, and fight autonomously, but aren't toilet trained
• Digimon need to be fed, trained (made to exercise), cleaned up after, and generally taken care of like a pet
• evolution (see below)
If a PCs is human, his Digimon should thus be both a Dependent and an Ally to him. Probably the other way round as well.
There's two fundamental approaches to evolution in Digimon: permanent evolution as found in the original v-pets, the Digimon World games, and some of the manga; and temporary evolution as depicted mainly in the anime. Either, however, are contingent of the Digimon being looked after properly, or at least being well-fed.
Temporary evolution could be handled by buying Alternate Forms (which, in turn, can receive Alternate Forms of their own). Each stage ought to have +1 Increased Consumption, or bleed FP and revert back to the previous form after FP drops below a certain threshold.
Permanent evolution could be done by allowing the player to spend points on an (inaccessible) alternate racial template. When the player is satisfied with it (and when it makes sense narratively), the Digimon evolves, permanently swapping racial templates to the one player has been working on (with a higher point total).
In either case, a Digimon's current form should be allowed to buy up attributes and skills, but forbidden from buying new Advantages; those should be locked behind evolution (ditto with DIsadvantages).