Here's who Gaara can beat:
No-Low diff: Zetsu, Hidan, Konan
Mid-High diff: Deidara, Sasori, Kakuzu
High+: 1 MS Obito, Kisame, and 6POP/Nagato
I've no idea why people deny the claim that 6POP < Gaara, based solely off of CT. CT can be avoided by staying out of range... I mean when have we seen a character who has the fastest aerial capabilities in manga sucked into CT before? Never. And are people forgetting CT requires the user to first eject a chakra sphere so the technique can work? It isn't just CT, GG. It's not that simple, not for Gaara anyways.
Kisame vs Gaara is my most hated match-up simply due to the fact neither can really hurt each other lmfao, though in the end it's clear Gaara has the advantage thus, Gaara wins as Kisame has no way of hitting him, while Kisame can just be spammed by sand techniques till eventually Gaara crushes a limb, or catches him off guard when he isn't using subterranean voyage etc.
If it's just one MS Obito, Gaara should be able to take him. Intangibility does nothing here, if Gaara just spams wave after wave. I'm sure everyone knows that... If it's double MS Obito he Kamui snipes him, and it's a neg diff.
I think Gaara can push Itachi, but all Itachi needs is one crow, and it's GG. Tsukuyomi crow gg. KA crow gg. Izanami crow gg.
TL;DR
Gaara solos.