Again, I don't think Pokryshkin or Hartmann would be able to keep up in a 1v1- they were smart, efficient fliers, but not necessarily good aerobatic fliers.
And Galland only had 275 kills putting him behind Barkhorn. Although, if you DID put Galland, who served through the whole war and fought against every airforce, against Hartmann, who arrived in Russia in late '42 and fought almost only Russians, I think Galland would probably beat Hartmann handily.
(I kind of lol'd to my self as I was writing 'only had 275'
)
Pokryshkin and Hartmann indeed would be a close fight.