Switch to a debuff team consisting of poison and ignite
For example, water main's poison tai, karin, tobi, sasuke
Have a ninja like sasuke to change the barrier so he does not use his attacking mystery

I don't know the ninjas you got. A good way to avoid Gaara is by interupting his barrier so he can't use his mystery. You cant chase someone with Superarmor yet, so focus others in his team first.
There are several ways to interupt his barrier. For example use ninjas like Ao or Iruka, both ninjas have a prompt mystery and Gaara's barrier isnt. Another way would be replacing his barrier for example with a 3 star Sasuke.

I hope I could help you.

As someone above said, debuff teams work. Ninja who can remove shields or ninja who can keep up a steady going of ignite or poison to make their shields obsolete.