Two line-ups I've used and found extremely useful consist of either Azure Fang, Kimimaro, Mabui, and Sai GNW. Or AZ, Sailor Sakura, Iruka, and Choji (GNW is better, but Shippuden also works).

The first ones set up is:

x-AZ-Kimimaru

x-Mabui-Sai GNW

Talents: 3-2-3-2-2

Summons: Ninja Monkey or Monkey King

You should get a decent combo rate with this and be able to cause interruption or chaos to one unit per round since there's a fairly high critical rate with this.

The second is:

Sailor Sakura-x-x

x-Iruka-x

x-AZ-Choji

Talents: 3-3-3-2-2

Summons: Lightning Tiger King or Basic Tiger

Iruka and Choji once again stop attacks from the other team and S Sakura and Azure provide support as well as S Sakura causing mass poison with her standard.

I was capable of getting Sailor Sakura and Iruka as a free to play by saving coupons for about two and a half months. So it is entirely possible if you choose to use this line-up.