Depends on the versions.

Prime Dio

And which alucard?

Main Timeline Alucard

Win at what?

It would take Dio months if not years to waste all of three million lives inside of Alucard. Assuming of course that Dio would outright take Alucard seriously.

@Eye Lad alucard could use level zero, and die immediately. Also, Dio is way over the speed of light. Alucard is the speed of sound.

Cool, I never liked that overpowered discount Carmen Sandiego.