Your Ewoks are strong enough. They probably need more speed though. The key here is that under Chirpa lead, all of their basics generate 20% TM. And Elder is even more key because his basic generates additional TM for himself and his allies.
So make Elder as fast as you can, and prioritize him as the target of all your assist calls. Logray has high base speed and has a TM generating move for his whole team so he should be the fastest. Paploo gets a significant 25% speed bonus when he's not taunting which is important because he also calls an assist, so it pays to make him speedy too. Wicket is your damage weapon so mod for offense and speed. Chirpa gets whatever speed you have left.
I did it with the first five of these guys. There is hope.
https://i.imgur.com/jED7XQP.png