sasori knows all about gaara's abilities since he is from the same village and has yuura as a spy as gaara's captain for many years. he's not going to be caught off guard by anything imo.
hiruko (his main puppet) would get crushed easily by gaara but that only makes sasori bring out his third kazakage puppet who's kekki genki (imo) can beat gaara's sand manipulations. + the poison soaked in it + the poison gas the third can pump out.
The third kazekage can bend sand, and Gaara's sand protects him of it's own occord. Gaara would use sand coffin to beat sasori, he could use sand tsunami, or just turn into Shukaku, and crush sasori. Nothing of Sasori can get through Gaara's sand defence, and if he gets through he still has his sand armor. He could surround himself in sand, and the only things that we have seen go through was chidori, and i think kimmimaro's bone almost went through. Needles of sasori won't work, and his poison won't get near him. Gaara is just too much for Sasori to handle, and I know Sasori let himself die, but Chiyo and Sakura would have probably still beat Sasori, and if he can't beat them, then Gaara could handle Sasori.
At least I got someone backing me up. Deidara's bombs, Chidori, Kimmimaro's bones, and even though we haven't seen it happen, rasengan could break through Gaara's sand. Sasori is to slow and none of his moves can break through Gaara's rock hard sand.
Who's using ABC logic? If Kimimaro easily bulldozed through Gaara's sand what makes you think this can't pierce through it? At the end of the day its still just sand.
also sasori has water pumps that slice through solid rock im pretty sure it can get through the sand plus sasori has puppets plus explosions like paper bombs can get through garra's sand
__________________ Even if we are fallen is it wrong to fight for what you believe in?
We are True Avengers
Honestly, Gaara would probably win, he doesn't really have a way to get past Gaara's sand and does not have the luxury of being able to pussy his way to victory by killing the villagers of the Sand Village.
If Kimmimaro can bulldoze through Gaara's sand so easily (and his bones can be shattered) Sasori's Iron sand which is basically indestructable can pierce through it just as easily, and even a cut would be fatal against Sasori.