So I've been toying with the idea of me as a Gumdramon for a while now, and this is more or less what I've ended up with and the direction I want to go.

To sum it up; He was a ZeedMilleniummon in his past life. He was prevented from destroying space and time, and ended reborn as the Gumdramon he is now. Instead of having a digicore proper as most digimon do; he's got MoonMilleniummon dormant within. Thus all of these restraints were placed on him in order to keep the power in and MoonMilleniummon from awakening.