Guess I'll be the oddball and suggest GNW Sakura instead of curse tag ninjas like Jugo or Kimimaro. GNW Sakura is available in both the rank shop and the arena shop, meaning to say piecing her together and upgrading her star should be almost, if not quicker than regular elite instance grinding.

The idea here is that Sakura can benefit from Iruka's passive, while Sakura herself make up for the lack of shield with slugs and heal. I imagine it would go something like this:

Blank, MB, Blank

Blank, Iruka, Blank

Sasuke, Sakura, Blank

2, 2, 1, 1, 1, White Snake

You c*so consider leveling up so that you get your fourth standard. That way in round 1, you need not choose between Iruka's interrupt and Sasuke's barrier in exchange for MB's standard attack.