It causes that card to also be treated as a Digimon with X000 DP. For example, if a Tamer is also treated as a Digimon, it can attack like a standard Digimon, and it will gain inherited effects from cards stacked under it. However, even if a Tamer is played and then treated as a Digimon in the same turn, it can't attack during that turn.

The effect that later gives it a play cost, level, or DP overwrites the older effect. Any other effects later gained will be added. For example, if a Tamer is also treated as a Digimon with <Blocker> and 3000 DP from an "is also treated as a Digimon with 3000 DP, gains <Blocker>, and can't digivolve" effect, then it gains an "is also treated as a Digimon with 6000 DP, gains <Rush>, and can't digivolve" effect, that Tamer will also be treated as a Digimon with <Blocker>, <Rush>, and 6000 DP.