Definitely Gaara/Kankuro/Tsunade or Gaara/Kankuro/Kabuto. You can even auto with these teams and get to Six Paths easy - especially with GNW Kankuro. Talents: 33111 or 33131 with Repluse Tiger, Main at Move 2

Try Empress if you're completely F2P, may not be able to auto with this one but you can definitely win. You could even have a team with Hinata and GNW Kankuro I think. Tsunade for Double Debuff healing is great.