you said Gaara vs the 4 sound nins, not 2

against the 4 sound nins basically no one stands a chance alone, thats the way it is.
they're an effiecient team

which is why the author didnt make it the full genin team vs the full sound team, theres no way they could have won as a group vs the sound, thats why they made it split up one at a time fight, makes it more believable

also if you'd notice there is a point in which Gaara becomes useless, thats when his opponent is too fast for him, even in demon form.
all of the sound nins are faster then Lee/Sasuke and thats in their normal forms, at level 2 Gaara stands no chance