I'm not sure how well SoK could fare with offing Alucard considering the vampire's omnipresence gained from Schrodinger's abilities. While Alucard doesn't have the many souls in his body as he did pre-Schrodinger since they were cast away so the guy could retain his sense of self, the ability of omnipresence could make SoK incapable of harming the vampire. But at the same time, Alucard won't have means of killing off SoK.
The only person on the team who appears capable of offing SoK would be Shiki in her third personality as Akasha's avatar. Alucard and the Saint Seiya characters would have to occupy SoK long enough in battle for Shiki to go in for the kill.
While I see Saint of Killers having the edge in this battle, it would be possible for the team to win with great difficulty and losses, provided Shiki remains alive to inflict the killing blow.