Seeing as you didn't show ninjas I can give you a simple overview of what works in GNW.

Generally AOE line ups across the board work well- being able to throw in some cross field shield & buff Ninja is also very beneficial, Earth Main can be beneficial for this as shields stack & an Earth Main c*so cross field shield everybody with a Talent.
Keep in mind that it does make the whole team easily countered by something that can cross field cleanse shields & buffs such as a Han.

Due to this, a really good line up for a group of people is Ninjo like Roshi & Han which are incredibly beneficial- A good line up for all 3 teams would consist of everyone using Azure Fang, Roshi line ups with 1 person using Han, Roshis are suited for large scale encounters due to their scaling & they also have the added effect of hitting 9 units with their own mystery while destroying barriers.

Things such as Angel Konan is highly devastating in GNW and a whole field of them, as you can imagine, will be devastating.
Try to keep in mind things that have synergy together can help even in defeating stronger teams, it helps if you have at least one way of interrupting in your 3 teams in case the enemy brings a barrier- it's also beneficial to also bring your own barrier. Say for instance you do have a line of Angel Konans, a good strategy is for one of you to have a Gaara in some ones line up to activate a barrier that all your Konans can benefit from, this works for most combinations not just Konan.

Keep in mind that things like Mirror Vision from Fire Main can be cast onto other players, this is also a fair way to shield & cleanse a team that is under crowd control- it's also a decent way of shielding the crap out of someone who may get targeted.