Alucard see Naurto as a monster/human and therefore fights with that mindset.
Naruto is allowed to use every technique he has been shown to use. (Kurama's help allowed)
Round 1 Naruto before his death (by Madara extracting Kurama) vs Alucard lives are reduced to 100,000 allowed to go level 0.
Round 2: Naruto after receiving the Sages Chakra. (once the next chapters come out) live 1,000,000,000 already in level zero.
Valley of the end and can cause as much destruction as they can possibly do.