It's a pretty complex question if you think about it, because Sasuke's time in the Akatsuki is so brief and under false pretenses. He's never a true member in the sense that Itachi or Kisame were; he's an infiltrator using the organization's resources for his own revenge. He joins alongside his 'team Taka'—Suigetsu, Karin, and Jugo—but they're basically just his crew tagging along.
His primary role within the group's framework was to be a replacement for Orochimaru, whose ring he took. But he never really participates in any of the grand collection of the Tailed Beasts. He just shows up, uses their intel to find Itachi, fights him, and then immediately turns on them to go after the Eight-Tails. He's more like a rogue agent who briefly occupied a slot on the roster. After the Five Kage Summit, the Akatsuki, or what was left of it, basically saw him as a loose cannon and a target.
So yeah, in the grand scheme, his role is that of an antagonist who temporarily aligns with the villains, creating this great tension where you know his presence there is a ticking time bomb. It made that whole era of the story way more unpredictable.