Sound 4 should win this mid-high diff imo.
-Kidomaru's drilling arrow at full power should definitely go through Gaara's defence imo.
-Jirobo's massive rocks can be enhanced if he enters CM. I'm going to assume it's 2-3x the size even though the boosts of CM have always been more then that. Jirobo throws that shit at Gaara to block LoS.
-Tayuya's Genjutsu is also capable of temporarily paralysing Gaara. He'd be capable of leaving the Genjutsu because he can still move his sand while under it, but that doesn't mean much here. She can have her Doki release the spiritual worms which ignore Gaara's absolute defence and drain him from inside. This is by far the most lethal thing against Gaara's defence.
I see it going like this;
1. Tayuya's Genjutsu paralyses Gaara and he contemplates on what to do.
2. Jirobo throws the massive boulder and Kidomaru prepares his drilling arrow.
3. Tayuya summons the Doki while the massive boulder is blocking vision.
4. Gaara breaks out of the Genjutsu by crushing his finger.
5. Jirobo throws the Doton, Kidomaru fires his arrow a second later while Tayuya lets the spiritual worms follow Jirobo's boulder.
6. Gaara blocks the boulder with his sand no diff, but the worms go right through the boulder and his sand and drain his physical energy (he's surprised at this point, didn't see them coming).
7. Kidomaru's drilling arrow hits Gaara from behind while he's being drained of physical energy and stopping a boulder.
8. GG unstable savage boi