Well this is how I think the battle would go: (i'll word it out sort of like a manga)
The Requirements
Gaara is "happy" to find people to kill, but still emotionless as ever. TenTen shoots several kunai at the enemy, which get blocked by Gaara's sand to Team 2's amazement. Temari then whips out her fan and sends the 3 targets into a tree, which forces them hide behind cover. Neji: "Ugh... this isn't looking good.." Lee's mind: "Gai sensei... I have met the requirements." [Gai + Lee flashback]. Lee takes off his weights and Neji's team grins in anxiety. Kankuro: "Quit delaying the inevitable!" Kankuro sends out poison gas while Temari blows it to their direction. Neji gets tenten out of there while Lee appears right in Temari's face and kicks the fan out of her grip, sending it flying into the ground. He then kicks her into a tree and back-flips to face the 2 remaining enemies, using his wrist pose. /End Chapter
The rest is pretty much a Lee vs Gaara battle all over again. I'm not taking feats past the preliminary third round into consideration though, since they had time to learn these moves (especially in the Sasuke Retrieval Arc). Lee without gates was actually doing quite fine against Gaara, and could have won just by being in base considering that the armor carries a huge chakra demand. Lee didn't have knowledge though, and tried a full on blast. So i'll assume he'd do the same here, except he'll have back-up so i'm giving it to Neji's team.