I mean it'd also have taken him thousands of years to get to the power level to defeat Bagramon himself
You severely misunderstand how Xros Wars worked, which is weird because the case of Darkknightmon is
actually and literally spelled out in the show itself. Skullknightmon was not going to get stronger, straight up, so he pioneered the Digixros to combine him with the one servant of his that was properly loyal to him, becoming Darkknightmon, and planned to eventually do it to Bagramon to steal his strength because Bagramon was stronger than he could ever hope to be. When he does this, the resultant combination is directly stated as being weaker than Bagramon was by himself by Shoutmon, which is corroborated by Bagramon just fucking murdering him within the combination soon afterwards and explaining to him and the audience that his central issue was his lack of conviction and ideals, and, as realized by how Bagramon was defeated two episodes later, a lack of friends to borrow strength from (which is also where Bagramon ended up falling, as all of his friends were dead by the time he went up against Shoutmon, all of his minions died by his own hand during the battle, and Shoutmon was able to call on significantly vaster wells of power beyond what should be physically possible to win anyway.).
