as it is gaara alone would win if its in the desert. but gaara can make a forest a desert in no time as shown in his fight with kimimaro. temari can forest bust with her sickle weasel but i dont see why that would benefit sand siblings. a forest is perfect for kankuro's traps and poisons to have maximum effectiveness. he has sasori puppet so he has all attacks sasori did and the mother and father puppets chiyo had. what does this grant kankuro? an underground puppet trap, flamethrowers, spinning blades, poison, an iron maiden trap capable of holding down even edo deidara, chakra barriers that withstood attacks from the third kazekage etc. given the forest location, i dont see how sharingan could even counter this as puppets arent alive. he could at best see the strings kankuros using to control them. and once hes figured that out, he will have either powerful sand missiles coming at his face, or sand prison attacking from below and behind. gaara will be able to mind**** sasuke by hengeing his sand clone into itachi and then when itachis destroyed, all it will do is turn the clone back into gaara's weapon, this time 2 feet away. effectively he holds a huge advantage by being able to do this. sure sharingan could probably tell the difference, but yeah. unlike normal clones, what it disperses back into is still a weapon for gaara. his sensor sand ensures sasuke cant hide. placing a few particles ensures this.
temaris fuutons were strong enough to cut up 3rd raikage. nuff said.
we've seen that sand can withstand amaterasu and gaara will no doubt protect his brother and sister by keeping a sand shield on them.