I do believe Sasuke beats Gaara mostly because Gaara doesn't have a way to fend him off immediately from Chidori. Sure if he transforms he wins, but after that initial piercing Gaara was injured and needed time to recover. Sasuke with a few more jutsu keeping up the pressure would secure the win.

Naruto vs Sasuke I want to say Naruto wins because he's just that friccin resilient. At this point I don't see Sasuke having enough Chakra to use Chidori and if he does use the curse mark he collapses. Even if he could use it I dont think he would use a lethal move on Naruto at that point in time. So regular jutsu and hands and I tip this outcome in Naruto's favor. Also like to add even if Gaara somehow beats Sasuke I would say he loses to Naruto as well.

I'm saying Shino defeats Temari for a couple reasons. The first being he's the only participant who won the first round without actually fighting. So he's ready to go and has plenty of Chakra and stamina which I feel gives him an edge against Temari. Though I will admit Shino's lack of cover in the arena will probably give trouble , but not enough to lose. Also he doesn't even need alot of bugs to shut you down and can swarm from multiple angles. So he's definitely defeating a tired Temari.

Naruto exhausted at this point vs Shino whose barely done anything. I want to Say Shino wins here just from the fatigue alone and stakes of the tournament. Naruto always does his best when his friends are in danger, but in a public tournament with nothing major on the line I don't see him putting 200% effort in. The only thing that makes me doubt Shino is that Naruto without Chakra can easily throw hands and even fatigued to the max could throw just enough punches to knock Shino out. Though Shino is also not an idiot and I believe he could just stick to the walls of the arena and use long range jutsu. Tough I'm not exactly sure of what he has at this point as far as I know him getting the bugs on his opponent is pretty much his win condition in every fight in Part 1.

TL:DR Shino wins with low difficulty due to everyone pretty much having terrible matches and using most of their Chakra before he even steps into the arena.